Is Your Tap Water Safe to Drink?

Most public water systems in the United States meet federal drinking water standards most of the time. But “meets the legal limit” and “contains nothing you would rather avoid” are not the same thing. This guide explains how US tap water is regulated, how to read the water quality report your utility publishes every year, and how to look up what has been detected where you live.

Quick answer: if you are on a public water system, your tap water must meet enforceable limits set by the US Environmental Protection Agency (EPA). Whether it is the water you want to drink depends on what your utility actually detects, how old your home’s plumbing is, and which benchmarks you use. Start with your utility’s annual report, then compare it with the state and contaminant pages linked below.

How US tap water is regulated

The Safe Drinking Water Act (1974, amended in 1986 and 1996) directs the EPA to set national standards for public water systems. Under the National Primary Drinking Water Regulations, the EPA sets legally enforceable standards for more than 90 contaminants, including microbes, disinfectants and their byproducts, inorganic chemicals such as arsenic and nitrate, organic chemicals, and radionuclides.

For each regulated contaminant, the EPA publishes two numbers:

MCLG (Maximum Contaminant Level Goal): the level below which there is no known or expected risk to health. It is a non-enforceable public health goal, and for some contaminants it is zero.
MCL (Maximum Contaminant Level): the enforceable legal limit. The EPA sets it as close to the MCLG as is feasible, taking into account available treatment technology and cost. For a few contaminants, such as lead and copper, the EPA requires a treatment technique instead of a numeric limit.

States and tribes with primary enforcement authority carry out these rules and can adopt stricter standards of their own. The EPA also publishes non-enforceable secondary standards for things that affect taste, odor or color, such as iron and manganese.

These rules cover public water systems. Private wells are not regulated under the Safe Drinking Water Act, so well owners are responsible for their own testing and treatment. The EPA’s private wells guidance is a good starting point.

What is a Consumer Confidence Report?

Every community water system must give its customers an annual water quality report, called a Consumer Confidence Report (CCR). It is due by July 1 each year and covers the previous calendar year. A CCR tells you:

where your water comes from (river, lake, reservoir or groundwater);
which regulated contaminants were detected, the highest level found and the range, next to the MCL and MCLG;
whether the system had any violations, and what it did about them;
lead and copper sampling results, plus required health information;
who to contact with questions.

You can usually find your CCR on your water utility’s website or through a link on your water bill. You can also search the EPA’s CCR information for consumers. If you rent, your landlord or building manager can tell you which utility serves the building. The EPA updated the CCR rule in 2024 to make reports easier to read. Starting in 2027, systems serving 10,000 or more people must send them twice a year.

Reading the units: ppm (parts per million) is the same as mg/L, ppb (parts per billion) is µg/L, and ppt (parts per trillion) is ng/L. One ppm equals 1,000 ppb, so check the units before comparing numbers.

Legal limits vs. health guidelines

An EPA legal limit is a regulatory decision. It weighs health research against what treatment can achieve and what it costs, and some limits have not been revised in decades. Health guidelines are different: they are non-regulatory benchmarks that some organizations publish to show a more protective level.

The best-known example is the Environmental Working Group (EWG), a nonprofit that publishes its own “health guidelines” in the EWG Tap Water Database. EWG’s health guidelines are EWG’s own benchmarks, not legal standards, and they are often far lower than EPA limits. For benzene, for example, the EPA legal limit is 5 ppb, and EWG’s health guideline is 0.15 ppb.

A result above an EPA MCL (on the basis the rule specifies, often a running annual average) is a violation. The utility must notify customers and correct it.
A result above an EWG health guideline but below the MCL is legal. It tells you the level is higher than EWG’s benchmark, which you may want to factor into decisions about filtration.

Two contaminants deserve a special mention:

Lead: the EPA’s health goal (MCLG) for lead is zero. Lead is regulated through a treatment technique and action level rather than an MCL, and it usually comes from service lines, solder and fixtures rather than from the treatment plant. That means your utility’s results may not reflect your own tap, so test at home if your building has older plumbing. See our lead in drinking water guide.
PFAS: in 2024 the EPA finalized the first national enforceable limits for several PFAS (“forever chemicals”), including 4.0 parts per trillion each for PFOA and PFOS. The EPA has since announced plans to revise parts of that rule and its compliance timeline, so check the EPA’s PFAS drinking water page for the current status. See cities with the highest PFAS levels.

How to check your tap water in three steps

Read your CCR. Look at the detected contaminants, the highest levels and any violations.
Look up your area. Find your state below, or search by ZIP code in our US Water Quality Database. Our reports compare detections against both EPA legal limits and EWG health guidelines.
Test at the tap if it matters to you. This is especially important for lead in older homes and for private wells. Use a state-certified laboratory for results you can rely on.

Check your state

Each state report summarizes what public water systems in that state have detected, with links to city-level reports.

Common contaminants, A–Z

Each guide explains what the contaminant is, where it comes from, how it is regulated and how to reduce it. Entries marked “(city rankings)” list the 25 US cities with the highest detected levels.

Reducing what’s in your water

If your report shows contaminants you would like to reduce, match the treatment to the contaminant. Look for a system that is certified to the relevant NSF/ANSI standard for that specific contaminant, and replace filters on schedule.

Echo whole-home filtration systems: treat all the water entering your home, including showers and laundry.
Echo reverse osmosis systems: point-of-use filtration for the water you drink and cook with.

Sources: US EPA National Primary Drinking Water Regulations and Consumer Confidence Report rule; EWG Tap Water Database (EWG health guidelines). This page is for general information and is not a substitute for testing or professional advice.