The Safe Drinking Water Act (SDWA) provides chemical and microbiological regulations for public water systems (PWSs) that must comply with the National Primary Drinking Water Regulations (NPDWRs).
Concisely the NPDWRs include the maximum contaminant levels (MCLs) for a list of organic and inorganic contaminants, radionuclides, and microbiological agents. These MCLs are enforced by the EPA for drinking water provided by community water systems and transient and non-transient non-community water systems.
The purpose of this enforcement is simple yet impactful: to protect public health from the toxic effects of the listed contaminants. These community and non-community PWSs serve drinking water to the majority of the population. Private wells, while they are not regulated by the SDWA, have ample of resources available to them by the state and federal agencies including by the CDC in what they could do to ensure the safety of their drinking water.
By the late 1800s, several PWSs in the United States used sand filtration technologies to clean water. However, bacteria and other microorganisms could not be trapped by the sand particles and due in part to the severe outbreaks of typhoid and cholera, drinking water treatment technologies evolved into the use of chlorination. Jersey City, in 1908, was the first to chlorinate drinking water and by 1941, chlorination was used by 85% of the PWSs in the United States.
The Public Health Service (PHS) established the first drinking water standards in 1914 and while these standards were revised and they eventually included more chemicals, drinking water enforcement was inadequate as found by a study in 1970 by the PHS. To address this, the SDWA was proposed and it was signed into law in 1974. Before the SDWA, there was another proposed title – the Pure Water Act – however the SDWA was eventually the preferred title.
The SDWA has been revised over the years to strengthen the enforcement of its regulations contained in the NPDWRs (Title 40, Chapter I, Subchapter D, Part 141) for PWSs that must be in compliance. The NPDWRs provide:
The PWSs that must comply with the SDWA are those that provide drinking water regularly to a minimum of 25 people or 15 service connections for at least 60 days per year. These PWSs include: community water systems and non-community water systems (transient and non-transient). They also include subpart H systems, which includes PWSs that use surface water or groundwater under the direct influence of surface water. The SDWA also applies to surface water, open bodies of water and subjected to surface runoff.
The NPDWR, the regulations that enforce the SDWA apply to each PWSs except if they meet all of the following conditions: they only consist of distribution and storage facilities and no treatment facilities; they are not owned or operated by a PWS, although they obtain their water from a PWS; they do not sell water and they are not carriers conveying passengers in interstate commerce.
Also, exemptions from certain provisions of the NPDWRs may be granted pursuant to certain sections as specified in the NPDWRs.
PWSs that provide drinking water and are covered in the NPDWR rely on the regulations to provide safe drinking water to their consumers, drinking water that have the listed regulated chemicals, disinfectant byproducts, and microorganisms below the limits as specified in the NPDWRs. Additionally, SDWA provides guidance about treatment techniques for compliance purposes, including filtration and disinfection and other techniques including in the microbial toolbox.
G uidance on treatment techniques to control corrosion in plumbing materials, how to prepare the CCR and how often to provide CCRs to their consumers, are also hallmarks of the act.
In general, the NPDWRs are relied upon by water treatment facilities and by PWSs as specified above that provide drinking water to community and non-community water systems all with the aim to provide safe drinking water. The SDWA is a crucial legislation for protecting the quality of drinking water provided by PWSs. It plays a major role in preventing diseases caused by water-borne microorganisms and toxicity from regulated chemicals listed in the NPDWRs.
Additionally, these regulations also provide the consumers with transparency about the state of their drinking water supply. The CCRs provide consumers with information about what is in their drinking water and the public notifications with information about the violations associated with the NPDWRs.
