How to test well water

Best for

Every private well owner, and especially homes with infants, pregnancy, a new well, recent well work or a change in taste, color or smell.

Wrong fit

Anyone hoping a home test strip or a salesperson's in-home demo will stand in for a certified lab. Use those only as a rough screen.

Tradeoff

A broad lab panel costs more up front, but a narrow one can miss the problem you are trying to treat.

Testing is your job

Private wells aren’t regulated like city water. EPA says the quality and safety of water from private domestic wells are not regulated by the federal government, and that private well owners are responsible for delivering safe drinking water to their households. About 15% of the U.S. population, over 43 million people, rely on private wells. CDC puts it the same way: as a well owner, you are responsible for testing.

Many problems have no taste, smell or color. Penn State Extension notes many pollutants in private water systems have no obvious symptoms and can only be found by lab testing.

Testing also catches problems early. Penn State reports that about half of Pennsylvania’s private water supplies have never been tested, and studies have found about 50% of private water systems fail at least one drinking water standard. Testing everything possible would be very expensive and isn’t necessary, Penn State adds. The better approach is a few standard tests plus targeted ones.

Step 1: Decide what to test

Start with a core panel, then add tests for what you see and what’s nearby.

Every year (CDC and EPA):

• Total coliform bacteria (plus E. coli if coliform is found)
• Nitrate
• pH
• Total dissolved solids (TDS)

At least once (Minnesota Department of Health):

• Arsenic
• Lead

When you see a symptom:

Based on land use. Penn State recommends testing every three years for pollutants tied to land uses within sight of your home, such as mining or gas well drilling. Your state health department or county extension office can tell you what’s common locally. You can also browse state guidance at /states/.

Step 2: Choose a certified lab

CDC says to use a state-certified laboratory. EPA says to use only labs certified for drinking water testing. EPA’s lab certification page links to each state’s certification program, and you can call your state program for guidance or contact a certified lab directly.

Penn State warns to be cautious of results from uncertified labs or from water treatment salespeople. If a vendor’s in-home test says you need equipment, confirm it with an independent certified lab before you buy.

You have three common routes:

• Your state, county or university lab. Often offers local drop-off, which helps with time-sensitive bacteria samples.
• A mail-in certified lab test, such as Tap Score, when you want a broad panel.
• A seller’s test kit. SpringWell, for example, requires a recent water test before it ships a well system.

See well water test kits compared for the trade-offs.

Step 3: Take the sample correctly

How you sample matters as much as which lab you use. Penn State’s instructions:

For any test

• Get proper containers and instructions from the lab. Never use old food or drink containers.
• Some bottles contain a preservative. Don’t rinse them or let them overflow if the instructions say so.

For bacteria

• Use the lab’s sterile bottle. It contains a chemical to neutralize chlorine.
• Remove the faucet aerator. Many labs suggest sterilizing the faucet tip with a flame or rubbing alcohol.
• Run the water for a few minutes, then fill the bottle without touching the inside of the cap or bottle. Don’t set the cap down.
• Keep it cool and get it to the lab within 24 hours.

For lead and copper

• Let water sit in the pipes at least 12 hours, then take a “first-draw” sample first thing in the morning, before any water is used.

Raw water vs. tap water

• The kitchen faucet tells you what you drink. If you already have treatment, it shows the treated water.
• To see what the well itself delivers, sample from the spigot at the pressure tank, before any equipment.
• To judge new equipment, test both.

Tests that need special handling

• Penn State says hydrogen sulfide must be tested in the home or chemically stabilized before shipping. Radon, Giardia and Cryptosporidium usually need a lab employee to collect the sample.

Check the well while you’re at it

Sampling day is a good time to look at the well itself. EPA’s private well guidance suggests:

• A well cap or sanitary seal to prevent unauthorized use of, or entry into, the well.
• A casing that sticks up above ground. EPA says not to cut the casing off below the land surface.
• Checking exposed parts for cracks, corrosion, a missing cap or settling around surface seals.
• Pumping and inspecting the septic system as often as your local health department recommends.
• Keeping chemicals away. Don’t put solvents, petroleum products or pesticides into a septic system or dry well.

A bacteria problem that comes with a loose cap or a casing at ground level is usually a well problem first. Fix it before you spend money on treatment.

Timing traps

• After shock chlorination. CDC says to wait 7 to 10 days, and until all chlorine is flushed, before sampling for bacteria. See shock chlorination.
• Legal or real estate needs. Penn State recommends that samples documenting water quality before mining, drilling or other disturbances be collected by an unbiased professional, so the results hold up.

Step 4: Read the results and act

When the report comes back, check each result against its limit, and pay attention to units and “less than” signs. Our guide to reading a well water test walks through a report line by line. To turn your numbers into a treatment plan, enter them at /test-results/.

Act on health results first:

• E. coli or total coliform present. Use bottled or boiled water for drinking. CDC advises a rolling boil for 1 minute until the water tests safe. Shock chlorinate, fix any defect and retest. See bacteria in well water.
• Nitrate above 10 mg/L (ppm). Don’t use the water for infant formula.
• Arsenic, lead or uranium above limits. Use other drinking water and call your state health department.

Then deal with nuisance problems such as iron, hardness and smell, where you have time to compare options.

Keep your results

File every report with the date, the lab and where the sample was taken. Penn State notes that data from earlier tests may be needed if you ever have to prove in court that a nearby land use damaged your water. Results over time also show trends a single test can’t. Penn State says TDS shouldn’t change much from one test to the next, and an increase could indicate pollution.

When to test again

CDC says to test more often, or for more contaminants, if there are problems with wells in your area, flooding or land disturbance nearby, a repair or replacement of any part of your well, a change in taste, color or smell, a pregnancy, or a child moving into the home. See how often to test well water for a full schedule.