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The term “water quality” refers to the characteristics of the water that include: chemical, physical, biological, and radiological characteristics. Water quality is a measure of the condition of water relative to the contaminants. In some cases, it examines the ability of water to support aquatic or biotic species as well as other needs such as drinking, bathing, washing, irrigation, industrial or other purposes.
It more commonly references a set of standards against which compliance is assessed through treatment of the water. The most common standards used to assess water quality relate to the health of ecosystems, the safety of human contact, and drinking water.
Drinking water quality standards describe the quality parameters set for drinking water. Even though every human on this planet needs drinking water to survive and that water may contain many harmful contaminants, there are no universally recognized and accepted international standards for drinking water. Even where standards do exist and are applied, the number, types and permitted concentrations of contaminants covered may vary significantly from one standard to another.
In the U.S., water quality standards include the Clean Water Act (CWA), which protects bodies of water with water quality standards guided by the desired uses for the water body (e.g., fish habitat, drinking water supply, recreational use).
The Safe Drinking Water Act (SDWA) covers water intended for human consumption and provides quality standards for public water treatment plants. The SDWA, the main federal law in the U.S. intended to ensure the quality of drinking water, is managed by the EPA, which sets standards for drinking water quality and oversees the states, localities and water suppliers who implement those standards.
States with primary enforcement responsibility, such as a Department of Environmental Quality or a Department of Natural Resources, are required to adopt drinking water regulations no less stringent than the national primary drinking water regulations set by SDWA 1413(a)(1).
States are not required to adopt secondary drinking water regulations. However, any regulations adopted should establish levels for contaminant as appropriate to their particular circumstances and local conditions, such as unavailability of alternate raw water sources or other compelling factors, provided that the levels adequately protect public health and welfare (44 FR 42195; July 17, 1979).
The American Water Works Association (AWWA) issues standards and guidelines covering construction of water treatment facilities and methods, water storage facilities, and public water mains and distribution systems. Generally, the organization’s standards are enforced by engineering specifications and field engineer inspections by civil engineering firms and city engineers, although some standards are referenced in codes and legislation. AWWA has its 2018 convention in Atlanta, Oct. 29-31.
Many countries in developed parts of the world have laws referencing or specifying standards for their citizens. For countries without a legislative or administrative framework for such standards, the World Health Organization (WHO) publishes guidelines for drinking water quality. It published “Guidelines for Drinking-Water Quality” in 2011.
The International Organization for Standardization published a regulation of water quality in the section of ICS 13.060, ranging from water sampling, drinking water, industrial class water, sewage and examination of water for chemical, physical or biological properties. ICS 91.140.60 covers the standards of public water supply systems titled “National specifications for ambient water and drinking water.”
Table 1. International and Country Standards for Drinking-Water Quality
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The map in below identifies countries where drinking water quality standards exist. Most are guidelines or targets rather than mandatory requirements. Few water standards have any legal basis or are subject to enforcement penalties.
The two exceptions with mandatory legal requirements are the European Drinking Water Directive (EDWD) and the United States’ SDWA. Both standards require legal compliance with the referenced standards in the legislation.
In the European Union, this includes a requirement for member countries to enact appropriate local legislation to mandate the directive in each country. The directive of the European Parliament and the Council on the Quality of Water Intended for Human Consumption require routine inspection and, where required, enforcement is enacted using penalties imposed by the European Commission on noncompliant nations. The European Parliament publishes the EDWD in 24 different languages for member countries to make it easy to implement.
The European Union codified its water policy in three directives:
Other countries with guidelines or number values for contaminants in their recommendations include Canada, which has guideline values for a relatively small number of contaminants. New Zealand also has a legislative basis, but I understand the language is not mandatory and water utility providers have to make "best efforts" to comply with the guidelines. I understand Australia has very good guidelines but has not adopted them as reference standards in their laws. China adopted its own drinking water standard, GB3838-2002 (Type II), enacted by the Ministry of Environmental Protection in 2002.
England and Wales in the U.K. specify acceptable levels for drinking water supply in the latest edition of the Water Supply (Water Quality) Regulations.
In India, the Indian Council of Medical Research Standards for Drinking Water is a voluntary standard and not required by legislation.
South Africa groups water-quality guidelines according to potential user types (e.g., domestic, industrial) in the 1996 Water Quality Guidelines. Drinking water quality is subject to the South African National Standard (SANS) 241 Drinking Water Specification.
Rotary International, along with various Rotary chapters, have journeyed to remote regions of Ghana for many years on mission trips to drill water wells and install sanitary facilities. There are no mandatory drinking water standards in Ghana because drinking water is not readily available in utility distribution systems beyond the city of Accra. Each year, Rotary chooses more villages along the contaminated waterways for these projects.
In 2016, I went on one of these trips. We installed water wells, elevated storage tanks and plumbing piping systems to hose valves near the water tower for gathering water for drinking, cooking and bathing. I saw the joy on the people’s faces when clean water flowed from the faucets during the commissioning ceremony. Before our visit, many villages collected water from nearby streams or rivers. Local mining operations have washed arsenic and cyanide, found naturally in their soil, into the waterways where it has poisoned and killed many unsuspecting villagers.
The new wells bring safe drinking water to an area where many die each year from bacteria-causing dysentery or other contaminants. Rotary scheduled another two-week mission trip for January; I hope to help with fundraising efforts and maybe go along again. Let me know if you are interested in joining us.
In the setting of standards, a government can form a committee to develop a guideline or standard to voluntarily comply with, or a technical organization or standards writing organization can become the secretariat of a standard and develop the standard for sale. Consensus standards are developed in an open process with public reviews if they follow the International Standard Organization or ANSI processes.
After development, government agencies typically review standards or rely on experts to advise on political and technical/scientific decisions about amendments or adopting standards with published levels of allowable contaminant levels related to the water quality for the intended purpose. There are standards for drinking water, effluent discharge from wastewater treatment plants and a host of other applications such as reclaimed water and greywater, describing treatment levels and what levels of contaminants are acceptable for a specified water quality application.
In the case of natural water bodies, standards can give guidance on how to maintain reasonably pristine conditions. Often stormwater retention ponds go a long way to help with reducing storm surges that cause erosion and silt, and they allow contaminants to settle in the pond before the water is slowly released into the waterway. Natural water bodies will vary in response to environmental conditions.
Environmental engineers and scientists must work with governments to understand how waste discharge into a lake can affect source water quality downstream. Knowing how to control the effluent levels for a wastewater treatment system helps to maintain the lake or river water quality as well as acceptable levels of contaminants discharged into waterways for downstream drinking water systems. Environmental engineers, environmental lawyers and policymakers work to define legislation with the intention of maintaining water at an appropriate quality for its identified use.
Most of the fresh surface water on Earth is not suitable for drinking and is not toxic. Seawater in the oceans covers the vast majority of the globe, but it is too salty to drink, and desalinization is a very expensive treatment process to meet drinking water requirements.
Another general perception of water quality is of a simple property that identifies polluted water. In fact, water quality is a complex subject, in part because water is a complex medium intrinsically tied to the ecology of our planet. Industrial and commercial activities — such as manufacturing, mining, construction and transportation — are major causes of water pollution, as are runoff from agricultural areas, urban runoff, and discharge of treated and untreated sewage.
Intended use determines the parameters for water quality. Work in the area of water quality focuses on water treated for human consumption, industrial use or in the environment.
1. Water for human consumption. Contaminants that may be in untreated water include microorganisms such as viruses, protozoa and bacteria; inorganic contaminants such as salts and metals; organic chemical contaminants from industrial processes and petroleum use; pesticides and herbicides; and radioactive contaminants. Water quality depends on the local geology and ecosystem, as well as human uses such as sewage dispersion, industrial pollution, use of water bodies as a heat sink and overuse, which may lower the level of the water.
The U.S. EPA limits the amounts of certain contaminants in tap water provided by U.S. public water systems. The SDWA authorizes EPA to issue two types of standards. Primary standards regulate substances potentially affecting human health. Secondary standards prescribe aesthetic qualities, those affecting taste, odor or appearance.
The U.S. Food and Drug Administration (FDA) regulations establish limits for contaminants in bottled water that must provide the same protection for public health. Drinking water, including bottled water, may reasonably be expected to contain at least small amounts of some contaminants. The presence of these contaminants does not necessarily indicate the water poses a health risk. Some bottled water companies have their water tested by NSF to assure the water meets the bottled water standards. Bottles carrying the NSF logo comply with the FDA water-quality standards for bottled water.
In urbanized areas around the world, water purification technology is used in municipal water systems to remove contaminants from the source water (surface water or groundwater) before distributed to homes, businesses, schools and other recipients. Water drawn directly from a stream, lake, well or aquifer that has no treatment process will be of uncertain quality.
2. Water for industrial and domestic use. Industrial uses for water include evaporative cooling, quenching and many other industrial processes. Contaminants in the water may need to be removed depending on the application. Iron filters remove iron. Dissolved minerals may affect the suitability of water for a range of industrial and domestic purposes. The most familiar of these is probably the presence of ions of calcium and magnesium, which interfere with the cleaning action of soap and can form hard sulfate and soft carbonate deposits in water heaters or boilers.
Hard water may be softened to remove these minerals with the use of a water softener. The softening process substitutes minerals for sodium cations. Hard water may be preferable to soft water for drinking. Softening decreases nutrition and may increase cleaning effectiveness. Softening can increase the efficiency of a water heater or boiler by minimizing the insulating layer of calcium and minerals that build up on heating surfaces.
Various industrial wastes and effluents can also pollute the water quality in receiving bodies of water. In the United States, waste discharge must comply with the Clean Water Act requirements.
3. Environmental water uses. Assessment of urban stormwater runoff discharging to coastal waters determines if it can cause damage to the environment and needs treatment. Environmental water quality, also called ambient water quality, relates to water bodies such as lakes, rivers and oceans. Water-quality standards for surface waters vary significantly due to different environmental conditions, ecosystems and intended human uses.
Toxic substances and high populations of certain microorganisms can present a health hazard for nondrinking purposes such as irrigation, swimming, fishing, rafting, boating and industrial uses. These conditions may also affect wildlife, which uses the water for drinking or as a habitat. Modern water-quality laws in advanced countries generally specify protection of fisheries and recreational use and require, as a minimum, maintaining the current water-quality standards. In the United States, wastewater discharge to lakes and other bodies of water must comply with the CWA requirements.
The following factors are often used to provide a measure of water quality: concentration of dissolved oxygen; levels of fecal coliform bacteria from human and animal wastes; concentrations of plant nutrients nitrogen and phosphorus; amount of particulate matter suspended in the water (turbidity); amount of salt (salinity); the concentration of chlorophyll, a green pigment found in microscopic algae; quantities of pesticides; herbicides; and heavy metals and other contaminants.
Most U.S. environmental laws focus on the designation of particular uses of a water body. In some countries, these designations allow for some level of water contamination as long as the particular type of contamination is not harmful to the designated uses. Given the landscape changes (e.g., land development, urbanization, clearcutting in forested areas) in the watersheds of many freshwater bodies, returning to pristine conditions would be a significant challenge.
In these cases, environmental scientists focus on achieving goals for maintaining healthy ecosystems and may concentrate on the protection of populations of endangered species and protecting human health. Stormwater retention ponds are good for allowing silt and debris to settle out of the water in a pond before slowly discharging downstream at a controlled rate.
The many types of measurements of water-quality indicators indicate the complexity of water quality as a subject. On-site measurements of water quality are the most accurate because water exists in equilibrium with its surroundings. Measurements commonly made on-site and in direct contact with the water source in question include temperature, pH, dissolved oxygen, conductivity, oxygen reduction potential, turbidity and Secchi disk depth.
There is enough information on sample collecting techniques to fill this magazine. However, on-site testing usually yields more accurate results.
The following is a list of drinking water quality indicators often measured by situational category: alkalinity; color of water; pH; taste and odor (geosmin, 2-Methylisoborneol); dissolved metals and salts (sodium, chloride, potassium, calcium, manganese and magnesium); microorganisms such as fecal coliform bacteria (Escherichia coli), Cryptosporidium, and Giardia lamblia; dissolved metals and metalloids (lead, mercury, arsenic, etc.); dissolved organics; colored dissolved organic matter; dissolved organic carbon; radon; heavy metals; pharmaceuticals (traces of drugs); and hormone analogs.
The three qualities of environmental water quality indicators are:
Many people in the industry have water-quality concerns for the near future. Currently, the U.S. is facing a water-quality dilemma. Water is treated at the treatment plan to meet EPA standards, but the quality goes down near the ends of utility water distribution systems. Water quality suffers because of mandated water conservation codes, standards, ordinances and voluntary water-use reduction programs.
These water flow reductions are causing aging water in the water mains. Well-intentioned water conservation efforts have the unintentional consequences of causing water to flow much slower in the water mains, causing significant delays in the transport of the water. In many areas, the water flows today are about 20 percent of the water flows before the flow reductions mandated in the Energy Policy Act of 1992 (EPACT 1992).
Before 1992, it would take water three to four days to travel from the water treatment plant to the end of a water distribution system. Now it can take 15 to 20 days for the water to reach the end of the system. Chlorine or other oxidizing water treatment chemicals added at the treatment plant typically dissipate within a few days depending on temperature, pipe materials, water quality and water treatment chemical type. The aging water issue is causing an increase in microbial growth in water distribution systems. Published reports from the CDC show a significant increase in the number of reported cases of Legionnaires’ disease over the same period of EPACT 1992 and additional water conservation programs.
The lack of water treatment chemicals at the far ends of public water supplies is causing more and more hospitals, nursing homes, hotels and other facilities to add secondary drinking water treatment units at their building’s water service entrance location. These systems monitor the incoming chlorine or monochloramine levels and add water treatment chemicals to maintain effective levels to control Legionella and other microorganism growth in their building water distributing system.
Many states treat these secondary water treatment units as a public water treatment provider and require expensive licensing, monitoring and reporting as if the building owner was a public water supplier. The regulations can become burdensome and cost-prohibitive. A standard for secondary water treatment systems is needed to assure public health and safety and eliminate bureaucratic red tape. I hope to see an organization such as NSF step up and develop such a standard.
As water utilities struggle with lack of chlorine residuals at the far ends of distribution systems, many have switched to different chemicals such as monochloramines, which allow the utility to have a water treatment residual at the end of the system. However, they are not as effective as chlorine at killing bacteria and micro-organisms in water distribution systems. Water utilities should consider secondary treatment at points along the water utility distribution system — such as where booster pumps to boost the pressure are located — with advanced monitoring and injection technologies.
The following water quality issues are not covered by regulations but should be considered for good engineering design and future compliance regulations:
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