Before you begin. This procedure is general reference information, not professional advice. Equipment varies by manufacturer, model, and year. Always follow the documentation supplied with your equipment — where it differs from this page, follow the manufacturer. Verify that you have the tools, the working conditions, and the ability to do this task safely. If anything is unclear, if the equipment is damaged, or if the task exceeds your experience, stop and use a qualified professional. You are responsible for your own safety and for the outcome. This site accepts no liability for any loss, damage, or injury arising from the use of this information.
Specifications marked unverified could not be traced to a manufacturer source. Do not rely on them — obtain the value from your equipment documentation.
Summary
A private well is not covered by the rules that protect public water systems, and no government agency tests it for you. Testing on a fixed schedule is the only way to know whether your well water is safe to drink. Bacteria, nitrate, arsenic and radon can all be present with no color, taste or smell to warn you.
This page covers a fixed annual and three-year testing schedule, situations that call for testing sooner, and how to read a laboratory result. It does not cover well repair or water treatment. Follow the sample collection instructions your laboratory gives you for each test. If a result exceeds a health guideline, contact your local health department or a certified water-treatment professional.
Safety
NITRATE ABOVE THE EPA LIMIT CAN KILL AN INFANT UNDER SIX MONTHS OLD.
Nitrate reduces the oxygen in a baby's blood.
Necessary equipment
| Item | Note |
|---|---|
| Sample bottle from a certified laboratory | Use the exact bottle and preservative your laboratory supplies for each test. |
| Chain-of-custody form | Record the site, date, time and your name before you send the sample. |
| Cooler with ice optional | Cool the sample if the laboratory's instructions require it. |
| Gloves and eye protection optional | Wear these if the sample bottle contains an acid preservative. |
Choose what tests to do and how often
Estimated 8 min to 19 min
Source: Guidelines for Testing Well Water · tier 1 · accessed 2026-08-04
Source: Natural Radionuclides in Private Wells · tier 1 · accessed 2026-08-04
- Do a yearly test of your well water for coliform bacteria and nitrate, and for total dissolved solids and pH.2mReport a problem with step 1, Choose what tests to do and how often
- Coliform bacteria are a sign of harmful organisms in your water.
- The pH value shows if your water is acidic or basic.
- Total dissolved solids show the amount of mineral matter in your water.
- Do a test of your well water for radionuclides once every three years.<1mReport a problem with step 2, Choose what tests to do and how often
- Radionuclides are radioactive elements that occur naturally in rock and soil.
- Contact your state radiation program to find the right test.
- Ask your local health department to name other substances for your test panel.5mReport a problem with step 3, Choose what tests to do and how often
- Farms, mines, or petroleum storage nearby can add substances to the list.
- Old pipes with lead parts can add lead and copper to the list.
- Do a new test of your well water if conditions near your well change.<1mReport a problem with step 4, Choose what tests to do and how often
- Do a new test after a flood, a land disturbance, or new construction near your well.
- Do a new test after any repair to your well or its equipment.
- Do a new test if the taste, color, or smell of your water changes.
- Do more frequent tests if an infant, small child, or pregnant person lives in your home.<1mReport a problem with step 5, Choose what tests to do and how often
- These groups are more vulnerable to contaminants in drinking water than others.
Find a certified laboratory
Estimated 8 min to 20 min
- Find a laboratory in your state certified for drinking water tests.5mReport a problem with step 1, Find a certified laboratory
- Contact your state or local health department for a list of certified laboratories.
- Some health departments do well water tests at low cost or no cost.
- Ask the laboratory about bottles, preservatives, and instructions for each test.3mReport a problem with step 2, Find a certified laboratory
- Different tests need different bottles, preservatives, and holding times.
- Get your sample supplies from the laboratory that will run the test.
Collect the water sample
Estimated 13 min to 43 min
- Choose a cold water faucet with no screen, hose, or filter attached.1mReport a problem with step 1, Collect the water sample
- Do a check of the faucet for cleanliness and leaks.
- Open the faucet.<1mReport a problem with step 2, Collect the water sample
- Allow the water to run for the time the laboratory states.3mReport a problem with step 3, Collect the water sample
- The faucet removes the old water from the pipe before you collect the sample.
WEAR GLOVES AND EYE PROTECTION IF THE BOTTLE CONTAINS AN ACID PRESERVATIVE.
Contact with the preservative can burn your skin or eyes.
DO NOT TOUCH THE INSIDE OF THE SAMPLE BOTTLE OR ITS CAP.
Contact can add germs to the sample and give a false result.
- Follow the laboratory's instructions to fill the sample bottle.2mReport a problem with step 4, Collect the water sample
- Do not rinse a bottle that already contains a preservative.
- Rinse an empty bottle three times with sample water if it holds no preservative.
- Leave the headspace the laboratory's instructions state.
- Label the bottle and complete the chain-of-custody form.2mReport a problem with step 5, Collect the water sample
- Record the site, date, time, and your name on the form.
- If the laboratory's instructions need it, cool the sample.<1mReport a problem with step 6, Collect the water sample
- Place the sample in a cooler with ice.
- Deliver the sample to the laboratory within the holding time.5mReport a problem with step 7, Collect the water sample
- A late sample can give an inaccurate result.
Read the results and decide what to do
Estimated 11 min to 32 min
Source: National Primary Drinking Water Regulations · tier 1 · accessed 2026-08-04
- Compare each result to the laboratory's stated limit or a health guideline.1mReport a problem with step 1, Read the results and decide what to do
- The laboratory's report shows if a result is above a limit.
- If a result exceeds a health guideline, contact your local health department.5mReport a problem with step 2, Read the results and decide what to do
- Your health department can explain what a result means for your household.
- Ask a certified water-treatment professional how to treat water that fails a test.5mReport a problem with step 3, Read the results and decide what to do
- A professional can read the result and recommend the correct treatment.
Terminology
This page uses one term for each item and holds it throughout, as ASD-STE100 requires. Equipment sellers and other guides use the names below for the same parts.
- total coliform bacteria
- Also called: coliform bacteria, bacteria in well water, germs in well water
- nitrate
- Also called: nitrates in water, blue baby syndrome, nitrate poisoning
- total dissolved solids
- Also called: TDS, hardness, mineral content in water
- radionuclides
- Also called: radioactive elements in water, radium in well water, uranium in well water
- state-certified laboratory
- Also called: certified water testing lab, state lab, approved water testing lab
- private well
- Also called: water well, household well, domestic well, private drinking water well
- maximum contaminant level
- Also called: MCL, EPA water limit, drinking water standard
When to use a professional
This page explains the test schedule and how to read a result. It does not cover well repair or water treatment. Use a laboratory certified by your state for every test. If a result exceeds a health guideline, contact your local health department or a certified water-treatment professional. A professional can read the result and recommend the correct treatment.
Common questions
How often should I test my well water?
Test once a year for total coliform bacteria, nitrate, total dissolved solids, and pH. Test once every three years for radionuclides such as radium and uranium. Test again right away after flooding, a nearby land disturbance, or any repair to your well. Test more often if an infant, a pregnant person, or an elderly adult lives in your home, since these groups are more vulnerable to contaminants.
What should I test private well water for?
The CDC and EPA both recommend an annual panel of total coliform bacteria, nitrate, total dissolved solids, and pH for every private well. Every three years, add a radionuclide test for substances such as radium and uranium. Ask your local health department which other contaminants are common in your area, since nearby farming, mining, industrial sites, and older plumbing all change the list. A state-certified laboratory can tell you exactly which bottles and tests you need.
Is well water safe if it looks, tastes, and smells normal?
Not necessarily. Bacteria, nitrate, arsenic, and radon have no color, taste, or smell, so a well can be contaminated with no warning sign at all. Regular testing on a fixed schedule is the only reliable way to know your water is safe. A change in taste, color, or smell is still worth testing for, but its absence proves nothing on its own.
Why does nitrate in well water matter so much?
The EPA sets a nitrate limit of 10 milligrams per litre (measured as nitrogen) for drinking water. Infants under six months who drink water above that limit can become seriously ill, and in rare cases the illness is fatal. It is sometimes called blue baby syndrome, because it lowers the blood's ability to carry oxygen. Nitrate usually comes from fertilizer, wastewater systems, or animal waste reaching the groundwater around a well.
What is a state-certified laboratory and why does it matter?
A state-certified laboratory has been approved by your state to test drinking water and follows standard methods for accuracy. Your local or state health department keeps a list of certified laboratories in your area. Some health departments also test private wells directly, often at low cost or no cost. A result from an uncertified lab is a result nobody can rely on.
What do I do if my test result is above a health guideline?
Contact your local health department or a certified water-treatment professional. They can help confirm the result with a retest and recommend the right treatment for your specific water. Some issues, such as bacteria, can sometimes be addressed with disinfection; others need a different water source or ongoing filtration. This page covers testing and reading results only, not treatment.
My well was just repaired. Do I need to test again?
Yes. Test your well water again after any repair or replacement to any part of your well system, after nearby flooding or land disturbance, and any time you notice a change in taste, color, or smell.
Related procedures
Sources
Every specification on this page is traced to one of these sources. Tier 1 is a manufacturer document, a published standard, or a government safety authority. See Standards for the full tiering rule.
- Tier 1Guidelines for Testing Well Water
- Tier 1Protect Your Home's Water
- Tier 1Natural Radionuclides in Private Wells
- Tier 1National Primary Drinking Water Regulations
- Tier 1Quick Guide to Drinking Water Sample Collection (Second Edition, Update)
Revision history
Current version 1 · updated 2026-08-04 · next review due 2027-08-04
- v1 · 2026-08-04First draft. Scope is a fixed testing schedule for a private well (annual core panel, three-year radionuclide test, and situational retesting), the sample collection and submission process, and how to read a laboratory result. Well repair, well equipment, and water treatment are refused and routed to a certified professional. Five tier-1 sources, all fetched directly and read in full: CDC 'Guidelines for Testing Well Water', EPA 'Protect Your Home's Water', EPA RadTown 'Natural Radionuclides in Private Wells', EPA 'National Primary Drinking Water Regulations' (nitrate MCL table), and EPA Region 8 Laboratory 'Quick Guide to Drinking Water Sample Collection' (used only for non-numeric sample-collection technique, not for any verified value, since it is dated 2016 and is close to the archaic-source threshold). CDC and EPA agree exactly on the annual panel (coliform bacteria, nitrate, total dissolved solids, pH); no conflict to publish. All procedures written independently in Simplified Technical English after the sources were read and closed; no competitor page was read or drafted from. Sources are staged in data/sources-additions-test-private-well-water.json for merge by scripts/sources_admit.py.
Corrections to this page are listed in the public corrections log. Reports that are credible and not yet verified are listed in the public errata register, and an open one renders above the step it concerns.
Comments and corrections
Found an error? A correction with a manufacturer source is applied and logged publicly. You can also write to corrections@fixchecklist.com.
Every step above carries its own report control, which tags the report with that step so a correction reaches the right place. For anything about the procedure as a whole — the order of the sections, a step that is missing, something that did not match your equipment — use this: report something about this whole procedure.