How to Test Water Quality at Home

How to test water quality: four ways compared

In short, here is how to test water quality: choose the tests your water needs, have a state-certified laboratory run them, collect the sample exactly as the lab tells you, and compare each measured level with its benchmark. You can do most of that from home. What changes between the options below is who analyzes the water, and that decides what the result is good for.

EPA's advice for well owners is to use only laboratories that are certified to do drinking water testing, and CDC gives the same advice. A test you read yourself is a screening: it can tell you that a certified-lab test is worth doing, but it is not that test.

The steps below follow the first two rows, because they give you a result you can act on. If cost is the question, our guide to free water testing covers public programs and store tests.

Step by step: from choosing tests to reading results

1. Choose the tests

Penn State Extension says a test for everything is very expensive and unnecessary. CDC suggests spending time identifying likely problems first, and asking your health department which germs or chemicals are a concern where you live.

• Private well. CDC recommends testing at least once every year for total coliform bacteria, nitrates, total dissolved solids and pH, plus anything your health department flags locally. CDC also lists reasons to test outside that schedule, such as flooding near the well, a repair to the well system, a pregnancy in the household, or a change in your water's taste, color or smell.
• Public water. Your water system tests its water, but EPA's home water testing fact sheet notes that a system's lead tests give a system-wide picture and do not reflect the conditions at your own faucet. Testing the tap in your home is the only way to know whether lead from your plumbing is in your water.
• A sign you can see, smell or taste. EPA lists common conditions with the tests they call for. For example, plumbing that contains lead points to pH, lead and copper, and stained fixtures or laundry point to iron, copper and manganese.

Our water test finder turns your situation into a short list of tests, and our guide to types of water testing explains what each test checks.

2. Find a certified lab

EPA encourages anyone who wants their drinking water tested to contact a state-certified drinking water laboratory, and says it cannot test residential water on request itself. CDC says your local or state health or environmental department, or your county government, should have a list of the certified labs in your area, and that these departments often test for nitrates and total coliforms themselves. EPA notes that your local health department may test a private well for free.

Our directory of certified water testing labs lists labs certified for drinking water in the states we cover. Before you order, ask the lab which tests it is certified for and whether it sends a kit with bottles and instructions. Most do: EPA notes that most testing laboratories supply their own sample containers.

3. Collect the sample

The lab's instructions come first, because the bottle and the method differ by test. Penn State Extension stresses that the instructions must be followed carefully to get an accurate result. A few points apply to most tests:

• Use the lab's bottle. Never use a food or drink container. Some lab bottles hold a preservative that keeps the substance from breaking down, so do not rinse those bottles or let them overflow.
• Pick the right tap. Most samples come from the kitchen faucet. If you have treatment equipment, a kitchen sample shows the treated water; Penn State Extension suggests the spigot at the pressure tank if you want the raw water from your well.
• Bacteria. The bottle must be sterile. Many labs ask you to remove the faucet aerator, clean the end of the faucet, run the water for a few minutes and fill the bottle without touching the inside of the cap or bottle. Penn State Extension says to keep the sample cool and deliver it within 24 hours^[5], and that most labs will not accept bacteria samples on Fridays or before holidays.
• Lead and copper from plumbing. Penn State Extension describes a first-draw sample: water that has sat in the pipes for at least 12 hours^[5], taken first thing in the morning before anyone uses water.

Some tests need the lab to collect the sample. Penn State Extension names radon, Giardia, Cryptosporidium and hydrogen sulfide as tests that usually require a lab employee to visit. If a result might be used in a legal dispute, such as a baseline before nearby drilling or mining, Penn State and Purdue Extension both advise having an independent third party collect the sample.

4. Read your results

EPA says your report should include the concentration of each substance you tested for, and it may also show whether a level exceeds a national primary or secondary drinking water standard. Our guide to water test results explains units, non-detects and how to compare each number with its benchmark.

If a level is above a health-based standard, EPA advises contacting your health department and having your well retested to confirm the result. If every level is within its benchmark, no treatment is needed based on that result.

When a home test strip or meter makes sense

Home strips, color kits and meters are quick and cheap, and they have a place. Purdue Extension describes them as screening tests that show whether further testing is needed, and says a positive result should be followed up at a certified laboratory.

One case where a home test can be the better tool: chlorine in public water. Penn State Extension notes that residual chlorine dissipates, so it is often more accurate to test it quickly at home, and that simple test strips can do it.

We found no EPA, CDC or extension source that rates handheld meters. A meter reading you take yourself is not a certified-lab result either, so treat it the same way as a strip.

Use a certified lab instead of a home test when:

• You are deciding on treatment. EPA's fact sheet advises finding out what is in your water before contacting dealers, and Penn State Extension advises caution with results from uncertified labs or from water treatment salespeople. Purdue Extension says results from water treatment vendors should be considered no more reliable than home test kits.
• A screening shows something. Confirm it at a certified lab before you act on it.
• You need a record. Purdue Extension notes that results from home test kits are not likely to be admissible as evidence in a legal action, and recommends documenting water quality with a certified laboratory.
• A buyer, seller or lender asks for a test. Ask them which tests they need and who may collect the sample before you order.