Tap Water Testing

What your utility tests, and where its testing stops

Your water utility tests the water it delivers. It does not test the pipes and faucets inside your home, and for lead and copper those are what matter most. A test at your own tap is the only way to know what comes out of it.

Public water systems answer to federal rules. EPA's National Primary Drinking Water Regulations are legally enforceable standards and treatment techniques that apply to public water systems. Your utility samples its water, reports the results, and acts when a result crosses a limit. Your utility's annual report summarizes that work for the system as a whole. It is a useful document, but it describes the system, not your kitchen sink.

Lead and copper usually get in after the water leaves the plant. EPA explains that lead can enter drinking water when plumbing materials that contain lead corrode. The most common sources of lead in drinking water are lead pipes, faucets and fixtures. In homes with a lead service line, the pipe that connects the home to the water main, EPA says that pipe is typically the most significant source of lead in the water. Among homes without a lead service line, the most common problem is brass or chrome-plated brass faucets and plumbing joined with lead solder.

None of that plumbing belongs to the treatment plant or the mains in the street. Water can leave the plant with no lead in it and still pick some up on the last stretch to your glass. EPA's page on the Lead and Copper Rule Improvements puts it plainly: in drinking water, the primary source of lead is from pipes.

Lead and copper are regulated differently from most contaminants. Most drinking water standards set a maximum level for the water a system delivers. For lead and copper, EPA instead uses a treatment technique: systems must control how corrosive their water is, so it is less likely to pull metal out of the pipes it passes through. Utilities check whether that is working by sampling at customers' taps. If more than 10%^[1] of those tap samples exceed the action level, the system must take additional steps.

That design tells you something important. The action level is a trigger for the utility across its whole sampling pool. A system can meet the rule while some individual homes have higher results, because each home's service line, fittings and faucets are different, and your home may not be one of the homes your utility samples.

Change is under way, slowly. Under the Lead and Copper Rule Improvements, EPA is requiring drinking water systems across the country to identify and replace lead pipes within 10 years^[2]. That is good news, but it does not tell you about your own home today, and it does not touch the faucets and solder inside your walls.

What this means for you. If you want to know about lead or copper in the water you drink, your utility's annual report can't answer the question. A sample from your own tap, analyzed by a certified lab, can.

What to test at the tap

On a public water system, your utility already tests for the long list of contaminants that federal rules cover. The tests worth adding at home are the ones your own plumbing can change. For most homes on city water, that means lead and copper.

Lead. Lead is the main reason to test tap water at home. EPA notes that you cannot see, taste or smell lead dissolved in water, so testing is the only sure way of telling whether there are harmful quantities of lead in your drinking water. The EPA action level for lead is 0.015 mg/L^[1]. As the section above explains, that number is a trigger for utility action across its sampling, so a result below it is not the same as no lead. Our lead water test guide covers who should test first and how to read a result, and our page on lead in drinking water explains where it comes from and what the levels mean.

You have more reason to test for lead if:

• Your home has, or might have, a lead service line. EPA says lead pipes are more likely to be found in older cities and homes built before 1986^[3]. If you don't know what your service line is made of, ask your utility what it knows about the line at your address.
• Your home has older brass or chrome-plated brass faucets, or plumbing joined with lead solder.
• Your utility has told you about a lead service line replacement on your street or at your address.
• You have never tested, and you want a baseline you can compare against later.

Copper. Copper is regulated alongside lead under the same treatment technique. EPA issued the Lead and Copper Rule to address corrosion of lead and copper into drinking water, which is why both metals are measured at the tap rather than at the plant. The EPA action level for copper is 1.3 mg/L^[1]. If you are ordering a lead test anyway, ask the lab whether it can add copper to the same sample.

What you usually don't need. On a public system, there is rarely a reason to repeat the utility's full list at your tap. Bacteria, nitrate and most chemical tests are a much bigger question for private well owners, who have no utility testing for them; see our well water testing guide. If you are not sure which tests fit your home, you can build a test plan in a few questions.

A clean result is a good result. If your lab reports lead and copper below their action levels, or does not detect them, no treatment is needed based on that result. Keep the report so you can compare it with your next test.

How to take a tap water sample

For lead and copper, how you collect the sample changes the number you get. EPA notes that the more time water has been sitting in pipes, the more lead it may contain. That is why lead tests use a first-draw sample: the first water out of the tap after it has stood unused in your plumbing.

The steps below are the short version.

1. Order the kit first. Use the bottle and instructions from your lab or your utility. They are written for the method that lab uses, and they are the rule if anything here differs.
2. Let the water stand. Don't use any water in the home for the standing time your kit gives, often overnight.
3. Pick the tap you drink from. Use a cold-water kitchen or bathroom tap that you use for drinking or cooking.
4. Don't flush or clean first. Don't run the tap, and leave the aerator in place unless your kit says otherwise.
5. Fill the bottle with the first water. Open the cold tap and fill the bottle to the line right away.
6. Label and return it promptly. Write the date, time and tap, and send it back within the time your lab or utility gives you.

Some utility kits use more than one bottle, so you collect a second or third sample after the first. Follow the bottle order your kit gives. Our lead water test guide walks through each step in more detail, including the common mistakes that spoil a sample.

Lab or home kit? A state-certified lab measures the concentration of lead in your sample and reports a number you can compare with the action level and with your own earlier results. A kit you read yourself gives a quick screening result, not a measured concentration. If the answer will drive a decision about your plumbing or your family's drinking water, use a certified lab. Our water testing cost guide shows verified prices for lab tests, and our state lab directory lists certified labs by state.

Free lead test kits from utilities

Before you pay for a lead test, ask your water utility. Some utilities test residents' water for lead free of charge, and some mail kits to the homes they serve. Two programs we checked:

• DC Water offers annual free lead testing for its residential and commercial customers. The kit is mailed to your home, and you collect the samples yourself. It includes two sample bottles, detailed sampling instructions, and information and a questionnaire about your plumbing materials.
• Chicago's Department of Water Management lets residents register to request a free water test kit if they are concerned about the potential of elevated lead levels in their home's water. The kit consists of three bottles, a mailing box and instructions.

Both programs serve their own customers only. If you live elsewhere, ask your utility whether it runs a similar program, what the test reports and who analyzes the sample. Programs open, close and change their rules, so check with the utility directly rather than relying on a list. Our page on free water testing covers free lead testing kits and other free or low-cost public testing programs.

When a free kit is enough. A free utility test is a good first step for most homes on city water. If the result is below the action level, or lead is not detected, you have a baseline at no cost, and no treatment is needed based on that result.

When to pay for a lab test. Consider a test from a state-certified lab when your utility offers no program, when you want a second result to confirm a high one, or when you want to check whether a plumbing change worked. Order the same kind of sample from the same tap each time, so the results are comparable.

Your utility's own data

Your utility's annual report and its published sampling results are the right place to learn about the system that serves you: where the water comes from, what the utility tests for, and how its results compare with federal limits. They describe the water as the system delivers it, and the utility's own tap sampling across its service area.

Use them alongside your own test, not instead of it. Your utility's data tells you about the system; a sample from your own tap tells you what your plumbing adds. If your result is at or above the action level, contact your utility as well: it can tell you about your service line and any replacement program.

To look up what your utility has reported, you can use TapWaterData, a separate site.

Your utility's reported data on TapWaterData (opens in a new tab)

Source: TapWaterData