Drinking Water, Sanitation, and Health with Patterson
Ref: Glenn Patterson (2020). Drinking Water, Sanitation, and Health. JHU MS-ESP Course of Instruction (AS.420.629.81). Email: scampi162@gmail.com
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Summary
An overview of drinking water, sanitation, and health with Dr. Glenn Patterson, covering water sources, water contaminants, water treatments, and water law with supplementary collated articles.
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---Water Sources---
Most people in the US get their drinking water from the ~162K public water systems. The large systems tend to use surface water while the smaller systems tend to use groundwater. ~16% get their water from private domestic wells or self-supplied systems.
Public Water System: A water system with at least 15 service connections or serves at least 25 people per day for 60 days of the year.
Community Water System: A public water system that serves the same people year-round. Most residences including homes, apartments, and condominiums in cities, small towns, and mobile home parks are served by Community Water Systems (~55K in the US).
Non-Community Water System: A public water system that serves the public but does not serve the same people year-round. Two types:
Non-Transient Non-Community Water System: A non-community water system that serves the same people more than six months per year, but not year-round, for example, a school with its own water supply is considered a non-transient system (~20K in the US).
Transient Non-Community Water System: A non-community water system that serves the public but not the same individuals for more than six months, for example, a rest area or campground may be considered a transient water system (~95K in the US).
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Surface Water
Surface Water: Water sitting open on the Earth’s surface, includes rivers, lakes, seas, oceans, reservoirs.
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Groundwater
Aquifer: An underground formation of sand, silt, or permeable rock in which the pore spaces between the rock particles (or voids in a permeable rock such as limestone) are filled with water, so that the aquifer can provide water to wells in usable quantities.
Artesian Aquifer: An aquifer confined above by an impermeable layer of clay or impermeable rock, allowing pressure to build up in the aquifer under the confining layer. The pressure comes from the weight of the water in what's called the recharge zone.
Recharge Zone: A part of an aquifer where the confining bed is absent, and rainfall and snowmelt can percolate down from the surface into the aquifer. The weight of this water creates pressure in the confined part of the aquifer. A well that penetrates the confining layer encounters water under pressure in the artesian aquifer under the confining bed. The artesian pressure pushes water up the well. It may be pushed up part way to the surface, in which case it's called an artesian well, or it may be pushed all the way up to and above the surface, in which case it's called a flowing artesian well. The name artesian comes from the region of Artois, France, where artesian conditions were first figured out.
Potentiometric Surface: The level to which water rises after drilling through a confining bed into an artesian aquifer, which causes artesian pressure to move the groundwater upwards.
Well: A hole dug or drilled from the surface down to an aquifer, in which water flows from an aquifer into the well. In most wells, a pump in the bottom of the well pumps the water to the surface.
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---Contaminants---
Non-Point Pollution: Sources of contamination such as agricultural and urban runoff, leaking landfills and underground storage tanks add contamination to source water.
>780M acres in the US—an area twice the size of AK—is home to grazing livestock (mostly beef cattle).
Total Contaminant Concentration = Pesticides + VOCs
Pesticides: Fairly common in water sources, particular in streams and rivers as opposed to groundwater.
Food Quality Protection Act (FQPA): The primary Federal legislation controlling the registration and regulation of pesticides.
Cumulative Risk Assessment: Evaluating and estimating the potential human risks associated with multichemical and multi-pathway exposures to pesticides.
Volatile Organic Compounds (VOC): Gasoline and Additive (MTBE), TCE, PCE, Chrloform/Bioform (Disinfectant Biproducts).
Organic Wastewater Contaminants (OWC): Chemicals derived from everyday substances including soaps, lotions, detergents, brighteners, flame retardants, disinfectants, preservatives, repellants, plastics, dyes, fragrances, and pharmaceuticals.
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Pathogens
Many infectious diseases are caused by pathogens that occur in freshwater, and are often derived from human or animal feces that get into source water.
Zoonotic: Pathogens that can spread from animals to humans.
Pathogens of Concern
Bacteria: E. coli, Salmonella, Shigella, Campylobacter, Vibrio cholera, Salmonella typhi (typhoid).
Protozoa: Cryptosporidium, Giardia.
Virus: Hep-A, Enteroviruses, polioviruses, coxsackieviruses, echoviruses.
Enteroviruses are second only to the common cold (rhinoviruses) as causes of viral infections in humans.
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Chemicals
Arsenic: Occurs in compounds with O, S, and metals; as a byproduct of various industrial and agricultural applications such as metal smelting, pharmaceuticals, and pesticides. Most of the arsenic that occurs in ground water is derived from the weathering of naturally occurring deposits of arsenic-bearing minerals.
Long Term Exposure can cause cancer, hyperkeratosis (thickening of the skin), change in skin pigmentation, and various cancers.
Standard: .01mg/L.
2001: The US EPA passes the Arsenic Rule, changing the MCL to 10micrograms/liter (same as the WHO).
Lead (Pb): Chemically similar to Ca, and competes with Ca to be incorporated into the body in places where Ca would normally go, such as in bones. It also adsorbs to RBC’s and moves into soft tissue such as the brain. In the brain, it affects the frontal cortex, impacting cognitive functions such as learning and memory. Effects are long-lasting, and are especially harmful in children.
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Corrosion
Corrosion: The process by which metal is chemically eroded by water that aggressively reacts with the Pb and Cu pipes to break them down into tiny particles that can get suspended or dissolved in the water. Corrosion will occur anywhere a galvanic cell or field can be or has established. To establish the field all that is needed is two dissimilar metals that are connected directly or indirectly by an electrolyte, such as water. This is the same chemical reaction that occurs within a battery.
The corrosion process can result in the presence of toxic metals in your drinking water. These metals include chromium, copper, lead, and zinc. The following are the recommended maximum contaminant levels for regulated public water supplies for the aforementioned metals: chromium (0.05 ppm), copper (1 ppm), lead (0.05 ppm), and zinc (5 ppm). To protect the public, the EPA and PADEP requires public water supplies to be non-corrosive and the “Lead and Copper Rule” has set new action levels for lead and copper of 0.015 ppm and 1.3 ppm, respectively
The rate and extent of the corrosion depend on the degree of dissimilarity of the metals and the physical and chemical characteristics of the media, metal, and environment. In water that is soft, corrosion occurs because of the lack of dissolved cations, such as Ca and Mg in the water. In scale forming water, a precipitate or coating of Ca or Mg carbonate forms on the inside of the piping. This coating can inhibit the corrosion of the pipe because it acts as a barrier, but it can also cause the pipe to clog. Water with high levels of Na, Chrloide, or other ions will increase the conductivity of the water and promote corrosion. Corrosion can be accelerated by various means:
Low pH (acidic water) and high pH (alkaline water).
High flow rate within piping can cause physical corrosion.
High water temperature can increase biological rate of growth and chemical corrosion.
O and dissolved CO2 or other gasses can induce corrosion.
High dissolved solids, such as salts and sulfates, can induce chemical or bio-chemical corrosion.
If the mass ratio (CMSR) of chloride to sulfate is > 0.2, but < 0.5 there is an elevated concern, but if the CMSR is > 0.5 and the alkalinity of the water is less than 50 mg CaCO3/L the concern should be significant.
Corrosion related bacteria, high standard plate counts, and electrochemical corrosion can result in pinhole leaks and isolated corrosion and aesthetic water quality problems.
Presence of suspended solids, such as sand, sediment, corrosion by-products, and rust can aid in physical corrosion and damage and facilitate chemical and biochemical corrosion.
If it is necessary to flush or run your cold water in the morning for a few minutes before you drink because the water has a bitter taste, YOUR Water is probably CORROSIVE. If you see blue-green stains in your basins or some staining along the joints of your copper piping, YOUR Water is probably CORROSIVE. As corrosive water stands or seats in pipes or tanks, it leaches metals from the piping, tanks, well casing, or other metal surfaces that water is in contact. If you see pink standing on the water’s edge - this may not be corrosion, but pink bacteria. Pink bacteria is an airborne bacterium.
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Animal Feeding Operations (AFOs)
Animal Feeding Operation (AFO): A place where animals are confined and fed for 45 or more days per year and no crops or vegetation, or "post-harvest vegetation" (such as stubble) are grown during the normal growing season. This means that AFO's are places where the animal population is likely to be denser than is normally accommodated by a pasture, since food is brought in, and the ground is not covered with vegetation.
Concentrated Animal Feeding Operation (CAFO): An AFO with at least 1,000 animal units or has 301-1000 animal units and meets one of the following conditions:
Discharges pollutants from the facility to waters of the US through a ditch or some other man-made device or discharges stormwater runoff that may originate off-site but has an opportunity to pick up pollutants from the facility.
Animal Units: 1000 Animal Units = 1000 beef cattle, 700 mature dairy cattle, 2500 hogs, 500 horses, 10K sheep, 55K turkeys, 100K chickens (if the facility has a continuous overflow watering system), 30K chickens (if the facility has a liquid manure handling system), 5K ducks.
CAFOs require (per CWA) a National Pollutant Discharge Elimination System (NPDES) permit for wastewater discharge if its pollution discharge can be caused by a 24-hour storm with an average recurrence interval of 25 years or less. That means, for example, that a CAFO that pollutes a neighboring stream as a result of a day-long rain that comes about once every 15 years needs a permit.
CAFO regulations may wind up encouraging further concentration of animal feeding operations into larger operations, because it is often the large operations that can afford the cost of regulatory compliance.
In 1999 there were ~450,000 AFO's in the US and ~15,500 CAFO's.
AFO’s produce myriad contaminants include nitrates, pathogens, and salts. There is also concern over metals and pharmaceuticals, including hormones and antibiotics that are added to animal feed and wind up in waste. About half the antibiotics produced in the US are added to animal feed, mostly to promote extra growth rather than to treat active infections. Animal waste, like human waste, also contains large amounts of undigested organic matter, which can lead to depletion of dissolved O in rivers and lakes, which can lead to other water-quality problems such as unpleasant taste and odor, and release of metals from sediments.
Nitrates and phosphates are plant nutrients. In a reservoir they can cause algal blooms, which can deplete the reservoir of dissolved oxygen and suffocate aquatic life. Under the resulting anaerobic conditions, unpleasant odors are produced, and concentrations of some toxic substances can increase.
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---Water Treatment---
One of the primary goals of drinking-water treatment is to remove pathogens.
One of the most important functions of a sewage treatment plant is to reduce concentrations of BOD, to protect receiving waters from the risk of becoming depleted in dissolved oxygen, which is needed to support aquatic life.
Disinfectants
I-Tablets: An inorganic chemical that kills pathogens.
Boiling: Use of boiling water to kill pathogens.
Cl: An inorganic chemical that kills pathogens.
UV Sterilization: Use of UV radiation to kill pathogens.
Ozonation: Used to kill pathogens.
Reverse Osmosis: Used to kill pathogens.
Adsorption: Organic contaminants, unwanted coloring, and taste and-odor-causing compounds can stick to the surface of granular or powder activated carbon and are thus removed from the drinking water.
Filtration: Used to remove particles including clays, silts, natural organic matter, precipitates, Fe, Ma, and micro-organisms. Filtration clarifies water and enhances the effectiveness of disinfection.
Ion Exchange: Processes used to remove inorganic contaminants if they cannot be removed adequately by filtration or sedimentation. Ion exchange can be used to treat hard water. It can also be used to remove arsenic, chromium, excess fluoride, nitrates, radium, and U.
Flocculation/Sedimentation: Water treatment processes that combine or coagulate small particles into larger particles, which settle out of the water as sediment. Alum and Fe salts or synthetic organic polymers are generally used to promote coagulation.
Treatment Process
Screen: Removes large debris.
Filtration: Removes medium sized debris.
Sedimentation: Removes smaller debris.
Disinfection: Cl and similar disinfectants including chloramine are added in a tank called a contact chamber (‘clearwell’). Adequate mixing and contact time are ensured by directing the flow of water with a series of baffles.
Disinfection Byproducts (DBPs): Chloroform and other trihalomethanes (THMs) have been shown to increase the risk of cancer in animals and humans. DBPs form from oxidation and/or halogenation (combining with Cl or another halogen) of naturally occurring organic compounds derived from the decay of soils and vegetation.
Naturally occurring organic compounds, such as humic and fulvic acids, are known as DBP precursors.
1979: The US EPA establishes a MCL of 0.10 mg/L for total THM's in drinking water.
DBPs include Chloroform (the most common), trihalomethanes, haloacetonitriles, chlorophenols, and various chlorinated acids (for example, haloacetic acids), alcohols, aldehydes, and ketones.
Septic Tank with Leach Field System: Widely used in rural and suburban areas, uses water to carry wastes and a septic tank to settle out some of the solids and provide some degradation (by anaerobic bacteria, as opposed to the aerobic bacteria in soil). The final step is leaching of the effluent from the septic tank through an absorption field into soil, where the remaining aerobic decomposition takes place.
Trickling Filter: Primary effluent is sprayed over a bed of rocks and allowed to trickle through the bed, being treated by bacteria in a layer of scum on the rocks;
Activated Sludge: Soil bacteria and air bubbles are injected into a tank of primary effluent where aerobic decomposition takes place.
Typical Sewage Treatment Process:
Screen out large debris.
Pump uphill, if needed.
Activated sludge aeration.
Sludge settling.
Scum removal (sometimes filtration is added here).
Disinfection prior to discharge to river.
Sludge recovery and disposal on land.
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Aquifer Treatment
In many aquifers the water is naturally free of pathogens, due to isolation from pollution sources at the surface, long residence time underground, natural filtering action in the aquifer, and microbiological predators that eat bacteria. As a result, many users of well water do not need to disinfect their water.
Some wells tap groundwater that has been influenced by pollution from the surface. This can be the case with a shallow aquifer made of sand or limestone, with no overlying confining layer. These aquifers are vulnerable to contamination, especially if there are nearby sources of pollution, such as septic tank/leach fields, waste dumps, leaking underground storage tanks, or contaminated surface runoff that has a chance to infiltrate. Users of these vulnerable wells are well advised to disinfect their water. It can be done in two ways:
Periodically dump a solution of bleach water into the well and let it sit for a day or so, then flush it through the system.
Add a disinfecting device to the plumbing of the house, such as a chlorinator, or UV lamp. If the well is large enough to serve as a public water supply (>25 customers), it must be disinfected. Your question helps to underscore the importance of well owners periodically testing their wells to see if they contain detectable quantities of certain types of enteric bacteria that indicate the likely presence of pathogens.
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---Water Law---
In the US, states are responsible for governing water use.
Clean Water Act (CWA): Passed by the USG in 1972 to regulate the disposal of wastes, primarily to achieve fishable and swimmable water in US rivers and lakes. EPA may set standards for ambient water quality, that is, water quality in rivers, lakes, and aquifers (the CWA does not cover drinking-water standards).
Comprehensive Environmental Response, Compensation, and Liability Act (‘Superfund’): Passed by the USG in 1980 to establish a fund to pay for the clean-up of abandoned hazardous-waste sites, set the SDWA drinking-water standards as the goal for such clean-ups, and required industries to disclose to their communities what hazardous materials they use and store.
Safe Drinking Water Act (1974): Passed by the USG in 1974, the EPA is responsible for setting water treatment standards in all public water systems (~170,000) serving 25 people or more (private wells are not covered).
EPA sets maximum contaminant levels for naturally occurring and anthropogenic (human-made) contaminants. State standards may be more stringent than EPAs, but not less stringent. EPA may also set standards for drinking-water treatment.
EPA, States, Tribes, water systems, and the public work together to ensure the standards are met. States are responsible for monitoring the compliance of drinking-water systems, under general supervision of EPA. Violations of standards can result in fines or other legal actions.
EPA provides funding in the form of loans to water systems from State revolving funds and direct grants to State drinking-water programs.
1996 SDWA Amendment: A USG Amendment to the SDWA that requires the EPA to assess the potential for contamination of all source-water areas, and encourages States and water systems to work with the public on a voluntary basis to protect source water (“multi-barrier approach). The Amendment emphasizes the public's right to know where their drinking water comes from and what is in it.
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Surface Water Law
Riparian (‘Along a River’) Rights: The water law that dominates in the relatively humid E. US where water is generally plentiful. This doctrine holds that any landowner whose land touches a water source such as a river or lake has an equal right to withdraw whatever water he or she legitimately needs. People who do not own land touching water sources must enter into agreements with riparian owners to obtain water.
In times of drought, when there is not enough water to satisfy all the needs, all riparian owners are supposed to suffer equally in diminished water supply.
Prior Appropriation: The water law that dominates In the relatively dry W. US, where water is often in short supply. The first person to withdraw water and put it to a beneficial use has the most senior right to withdraw water from that source, and that senior water right may be passed along to heirs or sold. There is no requirement to own land, riparian or otherwise. Each user's water right is based on the date of his or her first withdrawal.
This doctrine was developed by miners in the W. mountains to settle squabbles over who was entitled to divert water from streams to wash gold and silver from sediments or the ground itself. The motto of this doctrine is "first in time, first in right".
When there is not enough water to satisfy all the rights, the most junior rights lose their water first, while the most senior rights continue to be fully satisfied.
Federal Reserved Water Right: A guarantee of water sufficient to meet needs on Native American Reservations.
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Groundwater Law
Right of Capture: “Right of the biggest pump”; in some states, "if you can pump it out, you can use it".
Prior Appropriation: Used by AZ and CO to regulate groundwater. AZ even requires that the total withdrawals from an aquifer not increase, so that new users must find some other user who can reduce their withdrawal.
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US Drinking Water Standards
Maximum Contaminant Level (MCL): The most common EPA drinking water standard; this is a concentration that must not be exceeded in finished drinking water. EPA sets this level based on studies of the occurrence of the contaminant, the feasibility of removing it with current treatment technology, the health effects it causes, and the costs of regulation and treatment.
Primary Drinking Water Standards: Legally enforceable limits set by EPA to protect the public from contaminants that threaten health.
Secondary Drinking Water Standards: Non-enforceable guidelines recommended to protect drinking water from contaminants that cause aesthetic or cosmetic problems but are not threats to health.
If tests show a certain percentage of tap water samples exceed an action level of 0.015 mg/L for Pb or 1.3 mg/L for Cu, the water system must take additional steps that may include additional monitoring, corrosion control, public education, and replacement of lead service lines.
Bottled Water Regulations
Bottled water must meet the same EPA drinking-water standards as tap water.
Bottled water is regulated as a food product by the FDA under the 1938 Federal Food, Drug, and Cosmetic Act. Bottled water must meet the same FDA labeling requirements as food products.
EPA National Drinking Water Standards: https://www.epa.gov/ground-water-and-drinking-water/national-primary-drinking-water-regulations#Organic
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US Water Rules
Ground Water Rule: Requires disinfection to kill microbes in GW from aquifers that are under the direct influence of surface water.
All public-supply systems using GW must undergo periodic sanitary surveys, in which key points of the treatment and distribution process are inspected to determine whether microbial contamination is present or could occur.
All GW systems that do not disinfect must undergo assessments of hydrogeologic sensitivity to determine whether microbial contamination of the aquifer is likely. Those systems that do not disinfect and that are found to be hydro-geologically sensitive must have their source water monitored for microbial contamination. GW systems that do disinfect must monitor their disinfection process to verify at least 4-log (99.99%) removal of viruses.
Surface Water Treatment Rule: Applies to systems that use SW or GW under the direct influence of SW. The first step is monitoring to identify systems that are particularly vulnerable to contamination with resistant pathogens such as Cryptosporidium. These systems will include those with a high likelihood of contamination of their source water, as well as surface water systems that do not provide filtration in the treatment process. They are required to provide additional treatment beyond the 2-log (99%) pathogen removal.
Disinfectant By-Product Rule: Published in the Federal Register in 2006 to protect drinking water from toxic by-products that can be formed during the disinfection process. The rule applies to all community water systems and non-transient non-community water systems that use a disinfectant other than UV light to kill microbes in finished water. Typical disinfectants include Cl and chloramines. When these disinfectants combine with naturally occurring, otherwise harmless decaying organic matter in water, unwanted by-products, some of which are toxic, can be formed. Examples include trihalomethanes and haloacetic acids. The rule is designed to protect consumers from these by-products by identifying points in the distribution system where concentrations might be high, and monitoring those locations to ensure that concentrations of the by-products do not exceed certain limits.
Unregulated Contaminant Monitoring Rule: Recognizes that there may be dangers from some contaminants that are currently unregulated, that is, for which no standards have been set. With thousands of new chemicals coming into use each year, it is only prudent to expect that many will show up in at least trace amounts in drinking water, and that some of these will have adverse health effects. The rule requires that large water systems and a sampling of small systems monitor their water for the presence of a group of currently unregulated compounds.
EPA Lead and Copper Rule: If Pb concentrations exceed an action level of 15 ppb or Cu concentrations exceed an action level of 1.3 ppm in more than 10% of customer taps sampled, the system must undertake a number of additional actions to control corrosion. If the action level for lead is exceeded, the system must also inform the public about steps they should take to protect their health and may have to replace lead service lines under their control.
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Source Water
Source-Water Assessment and Protection
States and local jurisdictions are encouraged, not required, to take measures to protect source water from these potential sources of contamination. Many protection measures, such as land-use and public-access controls, buffer strips, incentives to move chemical storage facilities or polluting industries out of source areas, and restrictions on use of certain chemicals have been implemented at the discretion of the local jurisdictions.
USC recognizes two important aspects of source-water protection:
In order to protect source water, you need to know where the source water area is, how the water moves, and what types of contaminants you need to protect the water from. To address this item, USC requires states, working with local water providers, to develop source water assessment plans (SWAPs) for every public water supply in the nation. Each SWAP includes three steps.
Delineation of the source water area.
Inventory of potential sources of contamination.
Evaluation of the intrinsic vulnerability of the aquifer to potential sources of contamination.
While USC can mandate actions to take care of aspect (1), it is politically necessary to leave actual protection measures to state and local governments. This is because source-water protection involves land-use decisions, and those decisions are controlled by state and local governments.
EPA Sourcewater Protection: https://www.epa.gov/sourcewaterprotection/assess-plan-and-protect-source-water
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2014 Flint Michigan Water Crisis
Flint’s water distribution system is over a century old and uses Pb pipes.
Phosphates are added to water supply to minimize corrosion of the pipes.
The Flint River has relatively high corrosivity, in part because drainage from winter highway salting operations runs off into the river.
To mitigate the risk of corrosion, especially in systems with corrosive water and pipes containing lead and copper, water utilities add chemicals that encourage the creation of a protective biofilm between the water and the pipe, and that reduce the corrosivity of the water. One of the primary corrosion control agents is phosphate.
Discussions about corrective action focused on selection of an appropriate water source, control of corrosion, adequate monitoring, and, over the long term, replacement of the old Pb pipes. Estimates to replace this infrastructure range from $60M to $1.5B over 15 years.
The precautionary principle calls for public officials to assume the problem is significant, take immediate steps to monitor and verify the situation, and to notify the public so that their health can receive maximum protection.
Chronology
2002-2015: Flint, MI is governed by a series of five different governor appointed emergency managers.
2013: Flint announces it will start purchasing water through a source connected to Lake Huron. Detroit, who had been supplying the water, pre-emptively cuts the water supply to Flint, a year before it’s ready to take water through the Lake Huron company.
25 Apr, 2014: Flint re-activates its >50yr old water treatment plan, taking water from the Flint River.
Spring, 2014: Flint, MI Water Crisis.
Aug, 2014: Bacteria such as E. coli and total coliforms were detected at significant levels in Flint water; probable indication that some of the pipes were breaking down to the extent that soil bacteria were getting into the water. In keeping with typical practice, the water utility advised customers to boil their water to kill these bacteria and any others. This may have helped to prevent cases of gastro-intestinal illness, but the boiling merely concentrated the lead. The water system also added more Cl to the water in an attempt to provide stronger disinfection, which increased the corrosivity of the Pb pipes.
Feb, 2015: Flint city water experts reports Pb concentrations of .104 mg/L (above the “action level” of .015 mg/L).
Sep, 2015: Flint issues an advisory about Pb in its water.
Oct, 2016: Flint switches back to Detroit provided water.
Flint Issues
A governance structure that insulated municipal leaders from the needs and desires of the citizens of the municipality.
Underhanded municipal financing that robbed the water supply fund in order to cover other municipal debts.
An emphasis on cutting costs and services instead of meeting the needs of the people.
A misunderstanding or intentional disregard of the risk mitigation requirements of the Lead and Copper Rule.
Aging infrastructure and lack of a plan for replacing it.
Disregard for the precautionary principle.
Willful concealment of monitoring results that ran counter to the wishes of municipal and state officials.
Disregard for and belittling of scientific results presented by unbiased academic researchers.
Disregard for the voices of the citizens who spoke up expressing concern over the quality of the drinking water.
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Water Solutions
Agriculture: Manure composting, manure to energy digesters, removal of manure from the watershed, suing farmers with records of poor waste management, restricting herd size, building new water treatment plants, requiring waste-management training and certification for dairy farmers, improving monitoring and research, developing a total maximum daily load for P, and providing financial assistance to farmers to improve waste management.
Policy: Purchasing land and ending polluting land use, regulating land use by owners, providing grants to landowners who take measures to curb pollution.
Primary Protection Zone: Within 400’ of reservoirs and 200’ of tributaries.
Secondary Protection Zone: Land between 200’- 400’ of tributaries, along with wetlands and flood plains near the reservoirs.
Academic: Monitoring source-water quality,
Infrastructure: Upgrading treatment plants, replacing old piping, improving water treatment and conveyance, redesign of roadway draining to remove stormwater and eliminate risk from transportation releases.
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Terminology
Colony Collapse Disorder (CCD): The collapse of bee colonies (~42% of US colonies in 2015 alone) due to several cascading factors including the use of pesticides, habitat loss, climate change which shifts the blooming of flowers, and disease in which pathogens carried by mites weaken bees.
Inorganic Compounds: A broad class of chemicals, which may come from natural or human-influenced sources, including salt, nitrate, perchlorate, cyanide, radionuclides, and metals such as arsenic, mercury, lead, and copper.
Lethal Dose 50 (LD-50): The lethal dose required to kill 50% of organisms". LD-50 is used to compute a concentration that represents a MCL, assuming a certain intake of water, a certain standard body mass, and a safety factor (usually a factor of 10).
Organic Compounds: Group of C-based chemicals including solvents, hydrocarbon fuels and fuel additives, pesticides, pharmaceuticals, hormones, plasticizers, flame retardants, dioxins, and other synthetic chemicals. It also includes naturally occurring compounds, derived from the decay of vegetation, that cause taste and odor problems, or that combine with disinfectants such as chlorine to create harmful disinfection by-products
Particulates: Sand, and clay, particle sized matter.
Pathogens: Microorganisms that cause disease.
Synergy: When two drugs enhance each other to produce an effect that is greater than the sum of the effects that each would produce separately.
Toxicological Endpoint: Contaminants that cause the same type of adverse health effect (e.g., cancer, endocrine disruption, birth defect, central-nervous system damage, etc.).
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Resources
Environmental Protection Agency (EPA): The USA’s lead agency for the protection of public drinking water systems. The EPA has developed a multi-faceted plan to help ensure the security of our drinking water from accidental or intentional releases of hazardous substances. The plan focuses on the following activities:
Detection: Discover the contaminant release--where, when, what, and how much?
Containment: Protect downstream intakes and taps, prevent spread if possible.
Decontamination: Remove or neutralize the contaminant.
Risk Communication: Let the appropriate people know the facts at the appropriate times.
Science and technology support, including guidelines, training, a database of potential agents and their characteristics, and a simulation tool to predict the dispersal of a contaminant through source-water or a distribution system.
EPA Water on Tap: https://nepis.epa.gov/Exe/ZyPURL.cgi?Dockey=P1008ZP0.TXT
National Water Quality Assessment (NAWQA) Program: Seeks to describe patterns and trends in the occurrence of a number of categories of contaminants in surface and ground water in the US. The groups include pesticides, volatile organic compounds, and metals and other inorganic compounds; https://www.usgs.gov/mission-areas/water-resources/science/national-water-quality-assessment-nawqa?qt-science_center_objects=0#qt-science_center_objects
NRDC Sustainable Beef Standards: https://www.nrdc.org/issues/create-sustainable-beef-standards
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Chronology
2002: The USG passes the Bioterrorism Act, setting forth requirements for vulnerability assessments on all public water supplies (JHU Drinking Water, Patterson).
2000: A large volume of Cyanide spills into Romania’s Tisza River in Romania after a berm on a mine-waste lagoon breaks. The Tisza connects with the Danube and is the source of drinking water for ~2M Hungarians (JHU Drinking Water, Patterson).
1998: POTUS Clinton issues Presidential Decision Directive 63, identifying 18 critical infrastructures including water supplies that require protection from terrorist attacks. The EPA is given the lead role for risk assessment, research, communication, and coordination of protective measures for water supply (JHU Drinking Water, Patterson).
1994-1995: Japanese religious cult Aum Shinrikyo, uses nerve agents, including sarin gas, in attacks on a residential area and the Tokyo subway, killing 12 (JHU Drinking Water, Patterson).
1993: Groundwater contaminated with Arsenic is discovered in Bangladesh (JHU Drinking Water, Patterson).
1989: US EPA enacts a Total Coliform Rule to protect against fecal contamination of water (JHU Drinking Water, Patterson).
Jan, 1988: An oil storage tank at the Ashland Oil Company in Floreffe, PA ruptures, releasing a large volume of diesel oil into the Monongahela River upstream of Pittsburgh, PA (JHU Drinking Water, Patterson).
1 Nov, 1986: A large volume of toxic chemicals mixed with firefighting water flows into the Rhine River after a chemical spill occurs at the Sandoz chemical warehouse in Basel, Switzerland (JHU Drinking Water, Patterson).
1984: The OR based Rajneesh cult uses salmonella bacteria to contaminate salad bars, sickening 750 voters in an attempt to influence an election (JHU Drinking Water, Patterson).
1980: The USG passes the Comprehensive Environmental Response, Compensation, and Liability Act ("Superfund"), establishing a fund to pay for the clean-up of abandoned hazardous-waste sites, set the SDWA drinking-water standards as the goal for such clean-ups, and required industries to disclose to their communities what hazardous materials they use and store (JHU Drinking Water, Patterson).
1974: The USG passes the Safe Drinking Water Act (SDWA), granting the EPA authority to set water quality standards that states must enforce in all public water systems (~170,000) serving 25 people or more (JHU Drinking Water, Patterson).
1996: The USG passes an amendment to the SDWA requiring the EPA to assess the potential for contamination of all source-water areas, and encourages States and water systems to work with the public on a voluntary basis to protect source water (“multi-barrier approach) (JHU Drinking Water, Patterson).
1972: The USG passes the Clean Water Act (CWA) to regulate the disposal of wastes, primarily to achieve fishable and swimmable water in US rivers and lakes. EPA may set standards for ambient water quality, that is, water quality in rivers, lakes, and aquifers (the CWA does not cover drinking-water standards) (JHU Drinking Water, Patterson).
1962: The US Public Health Service sets water standards regulating 28 different substances (JHU Drinking Water, Patterson).
1917: Chlorination is first used to treat public water systems in the USA and Canada (JHU Drinking Water, Patterson).
1914: The US Public Health Service sets standard for the bacteriological quality of drinking water (JHU Drinking Water, Patterson).
1912: The USG passes the Public Health Services Act, the first federal law encouraging treatment of drinking water to meet certain standards (JHU Drinking Water, Patterson).
26 Sep, 1908: Cl disinfection is introduced to the Jersey City water supply; the first in the USA. It results in the near virtual elimination of waterborne infectious diseases in the city (JHU Drinking Water, Patterson).
1899: The first rapid-sand filtration system is installed in the Little Falls Water Plant on the Passaic River to provide filtered water for the City of Paterson, NJ; it serves as a model for many other cities (JHU Drinking Water, Patterson).
1890s: Cl is first applied as a disinfectant in English water facilities (JHU Drinking Water, Patterson).
1884: German microbiologist Robert Koch isolates the pathogen Vibrio cholera from the Elbe River (JHU Drinking Water, Patterson).
1870's: French Dr. Louis Pasteur finds that a specific microbe was present in the pus from a certain type of sore in a number of patients, and was not present in normal blood. He confirms the microbes cause disease by introducing the same microbes into the blood of rabbits (JHU Drinking Water, Patterson).
1854: Cholera breaks out in London. Believed to be spread by noxious vapors, it kills 500 people in Soho alone over 10days. In an achievement that inaugurates the study of public-health geography, British anesthesiologist Dr. John Snow, maps the deaths, interviews the families, and plots their locations, finding that nearly all the deaths took place a within a short distance of one pump, on Broad Street. He took a sample of water from the pump, examined it under a microscope, and noticed "white, flocculent particles". Convinced that these were the cause of the epidemic, he took his results to the Parish Board of Guardians. They were reluctant to believe him, but they agreed to let him remove the handle from the pump. The epidemic subsided significantly when people stopped using this source of water (JHU Drinking Water, Patterson).
1852: London passes a Metropolitan Water Act, requiring filtration for all water supplied to the London area (JHU, Patterson).
1831: Asiatic Cholera breaks out in London; believed to be spread by noxious vapors (JHU Drinking Water, Patterson).
1810: English scientist Sir Humphry Davy’s first realizes Cl is a new element and names it (JHU Drinking Water, Patterson).
1804: Sand filtration is put into use in the first municipal water treatment plant in Paisley, Scotland (the distribution system for this water plant was a horse and cart). By 1829 slow sand filters were being used for some of London's drinking water (JHU Drinking Water, Patterson).
1774: The element Cl is first isolated and observed by Carl William Scheele, a German Chemist, in Sweden, however he mistakenly believes it to contain O (JHU Drinking Water, Patterson).
~1500 BCE: Egyptians reportedly begin using the chemical ‘alum’ to cause suspended particles to settle out of water (EPA, 2008).
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The History of Drinking Water by EPA
Ref: EPA (2008). The History of Drinking Water.
Ancient Sanskrit and Greek writings recommended water treatment methods such as filtering through charcoal, exposing to sunlight, boiling, and straining. Visible cloudiness (later ‘turbidity’) was the driving force behind the earliest water treatments, as many source waters contained particles that had an objectionable taste and appearance. To clarify water, the Egyptians reportedly used the chemical alum as early as 1500 B.C. to cause suspended particles to settle out of water.
The design of most drinking water treatment systems built in the U.S. during the early 1900s was driven by the need to reduce turbidity, thereby removing microbial contaminants that were causing typhoid, dysentery, and cholera epidemics.
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Drinking Water Treatment by EPA
Ref: EPA (1999). Drinking Water Treatment.
Public Water System (PWS): Provides safe, reliable drinking water to the communities they serve. Does not serve the same people year-round. Split into transit non-CWS and non-transient CWS.
Community Water Systems (CWS): serves the same people year round.
Currently, the nation’s community water systems (CWSs) and nontransient non-community water systems (NTNCWSs) must monitor for more than 83 contaminants. The major classes of contaminants include volatile organic compounds (VOCs), synthetic organic compounds (SOCs), inorganic compounds (IOCs), radionuclides, and microbial organisms (including bacteria)
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Drinking Water Treatment Plants in Winnipeg
Ref: City of Winnipeg (2013). Drinking Water Treatment Plant. https://www.youtube.com/watch?v=20VvpASC2sU
Winnipeg Drinking Water Treatment Process: Lake- Aqueduct- Reservoirs- Pumps- Water Treatment Facility- Sulphuric Acid to lower pH- Ferric Cl is added for coagulation- flocculation basins causing particles to collide and stick together- clumps are removed in dissolved air floatation tanks with tiny air bubbles which bring the clumps to the surface which are removed with surface skimmers- Ozonation with ozone contactors- Na bisulphate is added to remove excess ozone- filter tanks with biologically activated carbon to remove parasites and particles- chlorine contact chamber for second round of disinfection- NaOH is added to return pH to near 7- clear well for disinfection with UV lamps- Fl added to help prevent tooth decay- orthophosphate to help protect water pipes- pipes carry water to three large distribution stations. Settled out materials are returned to the process while the clumps are removed to landfills.
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The Water Treatment Process in Severn-Trent
Ref: Severn Trent (2009). The Water Treatment Process. https://www.youtube.com/watch?v=9z14l51ISwg&feature=related
Severn-Trent Water Treatment Process
Water passes through mesh screens.
Coagulant is added for flocculation in a flash mixer.
Floc forms into sludge and is separated in a clarifier.
Water is sand-filtered slowly.
Ozone is added for disinfection and filtered with Charcoal.
Cl is added as a final disinfectant (contact time).
pH Controls.
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Source Water Collaboration (SWC)
Ref: Unk. Source water Collaborative (SWC). A Call to Action: A Recommitment to Assessing and Protecting Sources of Drinking Water.
Discusses the importance of source water protection at all levels of Government.
Vision: All drinking water sources are adequately protected. As a result, the nation gains profound public health advantages as well as economic benefits.
Role of utilities, local government, state programs, federal government.
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Drinking Water Chlorination by McGuire
Ref: Michael McGuire (2018). Drinking Water Chlorination: A review of US Disinfection Practices and Issues. American Chemistry Council.
26 Sep, 1908: Cl disinfection is introduced to the Jersey City water supply; the first in the USA.
Before cities began routinely treating water with chlorine, starting in 1908 in Jersey City, New Jersey, cholera, typhoid fever, dysentery, and hepatitis killed thousands annually.
Today, there is a multi-barrier approach that includes protecting source water from contamination, appropriately filtering, disinfecting, and treating raw water, and ensuring safe distribution of treated water to consumers’ taps.
During the conventional treatment process, Cl is added to drinking water as elemental Cl (Cl gas), Na-hypochlorite solution (bleach), or dry Ca-hypochlorite. When applied to water, each of these disinfection methods forms free Cl, which destroys pathogenic (disease-causing) organisms.
In 2015, 884M people worldwide lacked access to a basic drinking water service, while 2.3B people lacked even basic sanitation facilities such as toilets or latrines (WHO, 2018a,b).
Drinking water systems must also control disinfection byproducts (DBPs)—chemical compounds formed unintentionally when oxidants like chlorine and other disinfectants react with naturally-occurring organic matter in source water. In 1974, EPA scientists and a Dutch researcher independently determined that drinking water chlorination could produce a group of DBPs known as trihalomethanes (THMs), including chloroform. EPA set the first regulatory limits for THMs in 1979.
Cholera: An acute and deadly diarrheal disease caused by Vibrio cholerae bacteria.
Alternative disinfectants (including oxidants chlorine dioxide, ozone, and UV radiation)
Water Treatment Process
Coagulation and Flocculation remove dirt and other particles and some natural organics in the raw water. Alum (Al sulfate) or other metal salts are added to raw water to form coagulated sticky masses called floc that attract other particles. Their combined weight causes the floc to sink during subsequent mixing and sedimentation.
Sedimentation of coagulated, heavy particles through gravity to the bottom of the solids settling basin.
Filtration of water from the sedimentation tank is accomplished by forcing water through sand, gravel, coal, activated carbon, or membranes to remove smaller solid particles not previously removed by sedimentation.
Disinfection by the addition of Cl destroys or inactivates microorganisms remaining after the preceding treatment processes. Additional Cl or chloramine may be applied to ensure an adequate disinfectant residual during storage or transportation throughout the distribution system to homes, schools, and businesses throughout the community.
Among disinfection techniques, chlorination is unique in that a pre-determined Cl concentration may be designed to remain in treated water as a measure of protection against (re)growth of microbes after leaving the drinking water system. In the event of a significant intrusion of pathogens resulting, for example, from a leaking or broken water main, the level of the average Cl residual will be insufficient to disinfect contaminated water. In such cases, monitoring the sudden drop in the free Cl residual provides a critical warning to drinking water system operators that there is a source of contamination in the distribution system.
Biological Growth Control—Cl disinfectants help eliminate slime bacteria, molds, and algae that commonly grow in water supply reservoirs, and help control and reduce microorganism-containing biofilms in water distribution systems. Chemical Control—Cl disinfectants react with NH3 and other nitrogenous compounds that have unpleasant tastes and hinder disinfection. They also help to remove Fe and manganese from raw water.
Upon adding Cl to water, two chemical species, collectively called free Cl, are formed. These species—hypochlorous acid (HOCl, electrically neutral) and hypochlorite ion (OCl–, electrically negative)—behave very differently. Hypochlorous acid is not only more reactive than the hypochlorite ion, but is also a stronger disinfectant and oxidant. Although the hypochlorite ion is less reactive, longer contact times can provide sufficient biocidal activity and disinfection. The ratio of hypochlorous acid to hypochlorite ion in water is determined by the pH. At low pH (below 7.5), hypochlorous acid dominates while at higher pH (just above neutrality) hypochlorite ion dominates. Thus, the speed and efficacy of Cl disinfection can be affected by the pH of the water being treated. Fortunately, bacteria and viruses are relatively susceptible to chlorination over a wide range of pH. However, treatment operators of surface water systems treating raw water contaminated by the chlorination-resistant Giardia often take advantage of the pH-hypochlorous acid relationship and decrease the pH to help ensure that the protozoan parasite is eliminated. Treatment operators may also maintain low pH because viruses and bacteria are more susceptible to disinfection by Cl at these lower pHs. Cryptospordium, a protozoan parasite, is not affected by conventional drinking water chlorination and must be specifically filtered or inactivated through ultraviolet radiation. Another reason for maintaining a predominance of hypochlorous acid during drinking water treatment is because bacterial pathogen surfaces typically carry a natural negative electrical charge and thus are more readily penetrated by the uncharged, electrically neutral hypochlorous acid than negatively charged hypochlorite ions.
Non-Cl Alternative Disinfectants
Ozone (O3) Gas: Generated onsite at drinking water systems by passing dry O or air through a system of high voltage electrodes. O3 is one of the strongest oxidants and disinfectants available. Its high reactivity and low solubility, however, make it difficult to apply and control in drinking water treatment. Contact chambers are fully contained and non-absorbed ozone must be destroyed prior to release to avoid corrosive and inhalation toxicity conditions. O3 is more often applied for oxidation purposes rather than disinfection alone.
ADVANTAGES: Strongest oxidant/disinfectant available, does not directly produce chlorinated DBPs, effective against cryptosporidium, used alone and in advanced oxidation processes to oxidize organic compounds, will react with algal- and cyanobacteria-produced toxins.
LIMITATIONS: Process operation and maintenance requires a higher level of technical competence, provides no residual disinfection, forms brominated DBPs by oxidation of bromide in the water, forms nonhalogenated DBPs (e.g., aldehydes), degrades more complex organic matter; more biodegradable compounds can enhance microbial (re)growth in distribution systems and increase DBP formation during chemical disinfection, higher costs than chlorination due to capital costs, air or O requirements, and electricity cost, difficult to control and monitor, particularly under variable load conditions.
Ultraviolet Radiation (UV) Radiation: A non-chemical disinfectant generated by mercury arc lamps. When UV light penetrates the cell wall of an organism, it damages genetic material, and kills the cell or prevents reproduction. UV radiation has been shown to effectively inactivate many pathogens when sufficient doses of appropriate wavelengths are applied. Efficacy is dependent upon the delivered dose, transmissivity of the water, lamp spectral output, and intensity.
ADVANTAGES: Effective at inactivating most viruses, bacterial spores, and protozoan (oo)cysts at appropriate dosages, no chemical generation, storage, or handling, effective against Cryptosporidium at low dosages, directly photolyzes nitrosamines and some other trace chemicals at appropriate doses and wavelengths.
LIMITATIONS: Provides no residual disinfection, higher doses of UV radiation are required to inactivate some viruses, difficult to monitor UV dosage and performance within a drinking water system, irradiated organisms can remain dormant and sometimes self-repair and reverse the destructive effects of UV radiation through a process called photo-reactivation, usually requires additional pretreatment steps to maintain high-clarity water to maximize UV disinfection, does not provide oxidation or taste and odor control, high cost of adding backup/emergency disinfection capacity, Hg lamps might pose a potable water and environmental toxicity risk; their output declines with time in use, will not react with algal- and cyanobacteria-produced toxins.
Chlorine-Based Alternative Disinfectants
Chloramine (Monochloramine, NH2Cl): Chemical compounds formed by combining a specific ratio of Cl and NH3 in water. Dichloramine and trichloramine are undesirable and ineffective disinfectants, so it is essential to carefully control the blending ratios and process.
Because chloramine is a weak disinfectant compared to chlorine, it is almost never used as a primary disinfectant. Chloramine provides a durable residual because it is much less reactive than chlorine gas or sodium hypochlorite. Chloramine reduces chlorinated DBP formation, but also produces different, less well-studied nitrogenous- DBPs, and possibly nitrate and nitrite. It can also be used to minimize some free chlorine-related taste and odor issues.
ADVANTAGES: Reduced formation of THMs, HAAs, and other chlorinated DBPs; will not oxidize bromide to hypobromite; therefore, brominated DBPs are not formed; more stable, lasting residual than free Cl; fewer dose-related taste and odor issues than free chlorine; excellent secondary disinfectant; can be potentially more effective than free chlorine at controlling indicator bacteria and biofilms in distribution systems; reduces Legionella in biofilms and helps protect distributed water from biofilm-related microorganism activity.
LIMITATIONS: Weaker disinfectant and oxidant than Cl by several orders of magnitude; requires much longer contact times than free Cl; greater potential to produce nitrosamine and other nitrogenous- DBPs; can contribute to nitrification, especially in extended retention distribution systems; requires shipment and handling of NH3 or NH3 compounds in addition to chlorinating chemicals; NH3 and chloramines are toxic to fish, and can cause problems unless removed, which is more difficult than removing a free chlorine residual; must be removed from water used for kidney dialysis; will not react with algal- and cyanobacteria-produced toxins.
Chlorine Dioxide Chlorine dioxide (ClO2): A gas that is generated onsite at drinking water treatment facilities from Na chlorite in specially designed generators. One common method of generating ClO2 is by dissolving Cl gas in water to produce hypochlorous acid and hydrochloric acid, followed by reacting the acids with Na chlorite. ClO2 properties are quite different from free Cl. In solution, it is a dissolved gas with lower solubility than Cl. Unlike Cl, ClO2 does not hydrolyze in water, although it will generate chlorite and chlorate in water; therefore, ClO2’s germicidal activity is relatively constant over a broad range of pH.
ClO2 is volatile and is easily stripped from solution, and is a strong primary disinfectant and a selective oxidant. Its main inorganic byproducts are chlorite and chlorate. Although ClO2 can produce an adequate residual, it is difficult to maintain, which is why it is rarely used for that purpose.
ADVANTAGES: Reasonably effective against Cryptosporidium; up to 5x faster than elemental Cl at inactivating Giardia; disinfection only slightly affected by pH; oes not directly form chlorinated DBPs (e.g., THMs, HAAs); does not oxidize bromide to hyprobromite (but can form bromate in sunlight); more effective than elemental Cl in treating some taste and odor problems; selective oxidant used for manganese oxidation.
LIMITATIONS: Inorganic DBP formation (chlorite, chlorate); highly volatile residuals; requires onsite generation equipment and handling of chemicals (sodium chlorite and potentially chlorine, sodium hypochlorite, or hydrochloric acid); requires advanced technical competence to operate and monitor equipment, product, and residuals; occasionally poses unique odor and taste problems from gas phase reactions; occupational inhalation toxicity risk; higher operating cost (sodium chlorite cost is high); will not react with algal or cyanobacteria-produced toxins.
Hypochlorite
ADVANTAGES: Storage and transport of salt rather than Cl gas or Na hypochlorite solution.
LIMITATIONS: Higher capital and operating cost due to electricity consumption for electrolysis and system maintenance; more complex processing and requires a higher level of maintenance and technical expertise; requires careful control of salt quality.
Calcium Hypochlorite Calcium hypochlorite (Ca(OCl)2): Used primarily in small treatment applications. It is a white, dry solid containing approximately 65% Cl and is commercially available in granular and tablet forms.
ADVANTAGES: More stable than Na hypochlorite, allowing longer storage, fewer training requirements and regulations than elemental Cl, will react with algal- and cyanobacteria- produced toxins.
LIMITATIONS: Dry chemical requires more handling than sodium hypochlorite; precipitated solids formed in solution complicate chemical feeding; higher chemical costs than elemental Cl; fire or explosive hazard if handled improperly; can contain chlorate, chlorite, and bromate.
Chlorination: Applied to water in one of three principal forms: elemental Cl (Cl gas), Na hypochlorite solution (liquid bleach), or dry Ca hypochlorite. Chlorinated isocyanurates are also used for some drinking water applications (but more commonly for swimming pool disinfection). All produce free Cl in water.
ADVANTAGES: Highly effective against bacterial and viral waterborne pathogens and some protozoa; provides a residual level of disinfectant to help protect against microbial (re)growth and to help control biofilm growth in the distribution system; easily applied, controlled, and monitored; operationally simple and highly reliable; the most cost-effective disinfectant.
LIMITATIONS: Disinfection byproduct formation (e.g., THMs, HAAs, and other DBPs); will oxidize bromide in water to hypobromite forming brominated DBPs; not effective against Cryptosporidium; requires transport and storage of chemicals.
Elemental Chlorine Gas (Cl2): One of the most commonly used form of Cl in drinking water systems. It is transported and stored as a liquefied gas under pressure. Water treatment facilities typically use Cl in 100- and 150-pound cylinders or 1-ton containers. Some large drinking water systems use Cl gas delivered in railroad tank cars or tanker trucks.
ADVANTAGES: Lowest cost and most energy efficient of all Cl-based disinfectants; unlimited shelf-life; does not add bromate; will react with algal- and cyanobacteria- produced toxins.
LIMITATIONS: Hazardous pressurized gas requires special handling and operator training; additional regulatory requirements, including EPA’s Risk Management Program and the OSHA’s Process Safety Management Standard.
Sodium Hypochlorite (Bleach, NaOCl): Produced by adding elemental Cl to NaOH. Typically, hypochlorite solutions for water treatment applications contain from 12 to 15% Cl, and are shipped in 1,000- to 5,000-gallon containers.
ADVANTAGES: Solution is less hazardous and easier to handle than elemental Cl (gas); fewer training requirements and regulations than Cl gas; will react with algal- and cyanobacteria- produced toxins.
LIMITATIONS: Limited shelf-life; degrades slowly over time to chlorate and then perchlorate during storage—particularly at warm temperatures; can contain bromate from electrolysis of bromide in the precursor salt; corrosive to some materials and more difficult to store than most solution chemicals; higher costs than elemental chlorine due to shipping (water) weight (~85%).
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Drinking Water: A History by Salzman
Ref: James Salzman (unk). Drinking Water: A History.
The EPA estimates we need $335B simply to maintain our drinking water systems.
Investment in water infrastructure is the answer.
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Lead Poisoning and the Fall of Rome by Bernstein
Ref: Lenny Bernstein (18 Feb, 2016). Lead Poisoning and the Fall of Rome. WAPO.
The Romans would boil down grapes into a variety of syrups, all of which had one thing in common, according to Nriagu's article in the New England Journal of Medicine: They were simmered slowly in Pb pots or Pb-lined Cu kettles. When the recipes were tested in modern days, they produced syrups with Pb concentrations of 240 to 1000 mg per liter. "One teaspoon (5ml) of such syrup would have been more than enough to cause chronic Pb-poisoning," Nriagu wrote.
By measuring Pb isotopes in the sediment of the Tiber River and Trajanic Harbor, they estimated that the piped water probably contained 100x as much Pb as local spring water.
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Understanding the Safe Drinking Water Act (SDWA) by EPA
Ref: EPA (1999). Understanding the Safe Drinking Water Act (SDWA).
SDWA was passed by USC in 1974 to protect public health by regulating the US public drinking water supply.
SDWA does not regulate private wells which serve <25 individuals.
SDWA authorizes the US EPA to set national health-based standards for drinking water to protect against both naturally-occurring and man-made contaminants that may be found in drinking water.
SDWA sets up multiple barriers against pollution. These barriers include: source water protection, treatment, distribution system integrity, and public information.
USEPA sets primary drinking water standards through a three-step process:
1) Identifies contaminants that may adversely affect public health and occur in drinking water with a frequency and at levels that pose a threat to public health. USEPA identifies these contaminants for further study, and determines contaminants to potentially regulate.
2) Determines a MCL goal for contaminants it decides to regulate. This goal is the level of a contaminant in drinking water below which there is no known or expected risk to health. These goals allow for a margin of safety.
3) Specifies a MCL, the maximum permissible level of a contaminant in drinking water which is delivered to any user of a public water system.
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Effective Strategies for Monitoring and Regulating Contaminants Sharing Pathways by Venkatsesan
Ref: Venkatesan & Halden (Sep, 2015). Effective Strategies for Monitoring and Regulating Contaminants Sharing Pathways of Toxicity. Journal of Public Health.
A promising approach is to combine specific bioassays with state-of-the-art chemical screening to identify chemicals and chemical mixtures sharing specific modes of action (MOAs) and pathways of toxicity (PoTs). This approach could be used to identify and regulate hazardous chemicals as classes or compound families, featuring similar biological end-points, such as endocrine disruption and mutagenicity.
One major concern with chemical mixtures is the possibility of inducing synergistic effects, whose overall effects exceed the sum of adverse impacts caused by individual exposures
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