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Water Quality in the United States

The safe and reliable water supply we enjoy across the U.S. is the result of decades of work by public and private institutions, and legislators. The essential nature of this work is the reason public water utilities, such as ours, are regulated.

But water quality isn’t something that can be taken for granted. We’re seeing that changes in our environment and the way we use water are having negative impacts on supply. And we’re more aware that what we put down our drains and throw into our rivers and lakes can have far-reaching impacts on water quality. So, the more we learn about water quality, the more we can ensure generations to come will enjoy the same quality of life we do.

Please visit the Water Quality Reports page for all testing results for your community.

The Safe Drinking Water Act (SDWA)

US-EPA-LogoIn 1974, the Safe Drinking Water Act (SDWA) was passed by the U.S. Congress. Its mandate is to protect the quality of the nation’s drinking water, and is administered by the U.S. Environmental Protection Agency (EPA). The Act covers all groundwater and surface water actually or potentially destined for human consumption. All regulated water utilities are governed by the SDWA, but private wells and bottled water are not.

The SDWA sets standards for water quality by identifying potentially harmful drinking water contaminants and setting allowable limits. These federal standards must be met by state and local legislators, however; these may enact more stringent standards or include contaminants not covered by the SDWA.

National Primary Drinking Water Regulations (NPDWRs)

The ‘Primary’ contaminants below are those the EPA monitors closely for potential human health impacts. Some contaminants, like microorganisms, can appear in any water supply, while others might be specific to an area, or even a single well.

Viruses and bacteria that may come from plant and animal contact, agricultural operations, septic systems, and sewage treatment plants. These contaminants are the most likely to lead to Boil Water Advisories. Examples: coliform bacteria, cryptosporidium, enteric viruses, giardia, legionella, etc.

Disinfectants & By-products
Elements that may be used in the treatment of drinking water or produced during the treatment process. Examples: chlorine, haloacetic acids, trihalomethanes, etc.

Inorganic Chemicals
Naturally occurring salts and metals, or from human activity, such as urban stormwater runoff, wastewater discharges, herbicides and pesticides, oil and gas production, mining, or agriculture. Examples: arsenic, copper, fluoride, lead, mercury, nitrate, nitrite, etc. 

Organic Chemicals
Manufactured synthetic and volatile organic chemicals, such as by-products of industrial processes, petroleum production, herbicides, pesticides, gas station discharges, urban stormwater runoff, and septic systems. Examples: benzene, dioxin, PCBs, styrene, toluene, vinyl chloride, Per- and polyfluoroalkyl substances (PFAS), etc.

Naturally occurring radioactive elements, or as the result of oil and gas production and mining activities. Examples: alpha particles, beta particles and photon emitters, radium, and uranium.

All drinking water (even bottled water) may contain minute amounts of contaminants, but their presence alone doesn’t mean they pose a health risk. In fact, in small quantities some can have health benefits and enhance water’s taste.

National Secondary Drinking Water Regulations (NSDWRs)

In addition to NPDWRs, the EPA issues guidelines for drinking water contaminants that may have aesthetic effects (taste, odor, or color), or may cause cosmetic effects in people, such as staining or discoloring skin and teeth. The EPA doesn’t require water systems to comply with these guidelines, however; states may choose to adopt and regulate them.

Contaminants of National Concern

Most chemical contaminants identified by the EPA are localized in their impact and can be traced to a single source. But two substances are more widespread. The first, the metal lead, is still present in many home plumbing systems. The second, Per- and polyfluoroalkyl substances (PFAS), are a new concern we’ve only just identified and beginning to understand. Learn more about these contaminants, and the response and actions of the EPA and water utilities, on the related pages.


Learn about lead in drinking water and why it's a public health priority

About Lead

Human Health Hazard Pictogram (PFAS)

Learn about PFAS chemicals and the response from the EPA and water utilities

About PFAS