Water Reuse

Drinking Water Legislation

Safe Drinking Water Act

The Safe Drinking Water Act (SDWA) is the major piece of legislation in the United States that is used to regulate drinking water. The overall goal of the legislation is to protect the public health of Americans by ensuring that all public water systems deliver clean and safe water consistently an reliably. SDWA was originally passed in 1974 and has since been reauthorized in 1986 and 1996.

SDWA applies to all public water systems (PWS) in the United States. It also defines and categorizes PWSs, since certain rules and regulations under SDWA vary based on type and size of PWS. First and foremost, a public water system is defined to be a system that has at least 15 service connections or serves a population of at least 25 people and is active for 60 or more days per year. Under this definition, there are more than 160,000 PWSs in the United States. These 160,000 PWSs are further divided into separate groups based on their characteristics. An important distinction that is made is the difference between Community Water System (CWS) and Non-Community Water System (NCWS). A CWS is a system that serves the same people year round. A CWS tends to be made up of systems that primarily serve people in homes, apartments and other places of residence. There are roughly 54,000 CWSs. NCWSs are further divided into two groups, Transient Non-Community Water Systems (TNCWS) and Non-Transient Non-Community Water Systems (NTNCWS). TNCWSs is a system that does not serve the same people throughout the year. An example of this kind of system is highway rest area or campground. There are 89,000 systems of this type. A NTNCWS is a system that serves the same people more than six months of the year, but not year round. A good example of this type of system is a school. There are about 20,000 systems of this type.

There are two main structures that are used by EPA when crafting drinking water regulations. The first involves the use of Maximum Contaminant Level Goals (MCLGs) and Maximum Contaminant Levels (MCLs). Under this approach, for the regulated contaminant in question, research is done to determine what concentration in drinking water "below which there is no known or expected risk to health." This level is known as the MCLG. Once the MCLG has been established, EPA can establish an MCL. An MCL is the legally enforceable standard. It is important to note that the MCL is often a higher concentration that the MCLG. This is because under SDWA, EPA is allowed to factor in available treatment proceudres and costs. Each PWS can decide for itself how to meet these MCLs, and monitoring and public notification activities are followed to ensure that MCLs are observed. This is the approach used for most of the contaminants regulated by EPA, especially chemical contaminants.

The second structure used in drinking water regulations is the Treatment Technique (TT) approach. Under this approach, certain treatment procedures are required in order to protect against contaminants. This approach is commonly used to guard against microbial contaminants. For example, various EPA regulations require filtering and disinfection as treatment techniques to reduce various microbial contaminants to safe levels.

Safe Drinking Water Act
Understanding the Safe Drinking Water Act. EPA Circular 816-F-04-030. June 2004.