Unit 19 Lecture Notes - Safe Drinking Water

The Safe Drinking Water Act (the Act), <http://www.epa.gov/safewater/>, was enacted by Congress in 1974 to protect the public from contaminated drinking water. It was substantially amended by the Safe Drinking Water Act Amendments of 1996. As with much of the federal environmental legislation that we study, the Act is implemented through delegation to the states. North Carolina has received delegation from the EPA and has implemented this delegation through the North Carolina Safe Drinking Water Act.

Coverage under the Act is limited to public water systems. The Act defines a public water system as one that has 15 service connections or regularly serves 25 or more people. Ownership of the system is irrelevant to the definition. Thus a building served by its own well would be a public water supply system if 25 or more people worked in the building and used the water.

The Act establishes certain requirements for public water supply systems. Operators must be trained and certified. Water quality testing must be conducted on a periodic basis. The number of people served determines the range of substances for which the water is to be tested and the frequency of testing. The more people served the more testing that is required. This has nothing to do with the relative safety of different sizes of public water systems. Larger systems can spread the cost of testing over more customers whereas the level of testing required of large systems might force the smaller systems out of business. The result would be that their customers would have to find an alternative source of water. The alternative to using water supplied by a public water system is usually a private well. Since private wells are virtually unregulated after their initial installation, private wells are usually even less safe than a small public system with minimal testing. Bottled water is often no safer than either a public water system or a private well since there is very little regulation of the bottled water industry. Where water is drawn from a surface water source, the operator must comply with the Surface Water Treatment Rule. There is no equivalent for water drawn from wells. The Act encourages but does not require that states adopt a well head protection program to protect aquifers that serve as sources of water for public water supply systems.

The contaminants (or categories of contaminants) for which testing is required include coliform bacteria, disinfection byproducts, inorganic chemicals, nitrates/nitrites, synthetic and volatile organic chemicals, flouride, lead and copper, radionucleotides (radionuclides), and asbestos.

The presence of coliform bacteria is an indicator that water has been contaminated with either human or animal waste. As coliform bacteria may be found in water without fecal contamination it is an imperfect indicator and may be revised as researchers develop better indicators. Testing must be at least monthly for all public water supply systems with more frequent testing required for larger systems. If the test is positive, the operator must notify DENR, Division of Environmental Health, Public Water Supply Section, <http://www.deh.enr.state.nc.us/pws/index.htm>. The operator must also notify the public including those using the system and follow established emergency procedures. The operator must then repeat the sampling and analysis, identify and correct the problem.

Drinking water is generally treated with chlorine or other disinfectants to kill harmful bacteria found in the water. While this process is essential to protect users of the water from pathogens, the process has the unintended consequence of introducing carcinogenic chemicals into the water. These chemicals are created when chlorine combines with organic compounds in the water. All systems serving 10,000 or more people must test for disinfection byproducts.

Testing must be conducted for other contaminants including inorganic chemicals, nitrates and nitrites, and synthetic and volatile organic chemicals. This last category includes pesticides and PCBs. System operators may also be required to test for flouride. Flourine is an element that, at low levels, makes children's teach resistant to decay. It is, therefore, added to waters that are deficient in it. At higher levels it is toxic. It is naturally occurring in some water sources. Lead and copper in water can come from various sources; however, they are usually introduced into the water from pipes in older houses. The copper comes from the pipes and the lead from the solder with which they are put together. Lead solder is now banned. Copper pipes are legal but not used much any more. Testing for lead and copper most accurately measures the problem when it done at the tap in people's homes. Many local governments provide testing at nominal cost. Radionucleotides result from radioactive decay of naturally occurring radioactive elements in the ground. Water must also be tested for these. Asbestos contamination may occur because asbestos is found naturally in the water or because it was introduced through human activities such as the existence of asbestos pipes in the water system.

When testing reveals violations both the public and the Public Water Supply Section must generally be notified.

Wellhead protection programs are not mandated but the Act but are highly advisable where a public water supply system is supplied from wells. States may mandate these programs based upon their own state laws. There are three primary tools used in wellhead protection programs. Zoning is used to exclude activities that might contaminate groundwater from the wellhead or land area near the well. Land use planning is also used to the same effect. And health regulations may also be used to prohibit certain activities that might contaminate groundwater.

The Act gives the EPA authority to mandate that states develop programs to protect surface water sources of drinking water. These are water supply watershed protection programs. These typically use the same tools used in wellhead protection programs. Zoning for lower density is particularly important as such zoning reduces the pollutant loading from runoff. The Act also mandates filtration and disinfection as required to protect the public health.

The SDWA reauthorization in 1996 strengthened source protection, promoted managerial, technical and financial capacity development in local water systems, and required operator certification. It also required that consumers be provided with more information about their water. Systems serving 10,000 or more people must provide annual consumer confidence reports to each customer. These reports disclose contaminants found in the water as the result of testing even if those contaminants exist at levels below legal limits. Systems serving 500 or more people but less than 10,000 may publish reports in a local newspaper with the permission of the governor of the state. Small systems (with less than 500 customers) are only required to provide public notice that the report is available. All system operators must report serious violations to their customers within 24 hours.