Informational vs Certified Well Water Testing: Test Strips vs a Certified Lab
Short answer: test strips and store-bought kits give you an informational result, a rough first look for your own use. A certified (compliance) result comes from a lab your state certifies for drinking water, using approved methods. When a law, a lender, a health department or a legal record needs the number, only a certified lab result counts. Last verified November 2, 2026.
What is informational well water testing?
Informational testing is any test you run just to learn about your water. Test strips, color-chart kits and small bacteria kits from a hardware store fall here. Some health departments hand them out too: Southwest Nebraska Public Health Department gives free nitrate and nitrite paper strips each May and September, and says they are "a simple way to start monitoring your well," but "not as accurate as lab testing."
The San Francisco Public Utilities Commission says home kits can give reasonable approximations if you follow the instructions carefully, but they can also mislead: a color strip or indicator line may not fully develop, the user may misread it, and lead kits can give variable results depending on the brand. Its advice is to treat a kit result as "an initial step, not a final result."
What is certified (compliance) testing?
EPA explains that states certify laboratories to test drinking water for compliance with federal drinking water rules, using methods EPA has evaluated and approved. Public water systems must use these labs. A private well owner isn't required to, but EPA's advice for wells is the same: "Only use laboratories that are certified to do drinking water testing."
Certification is given test by test. A lab can be certified for bacteria but not for arsenic or PFAS, so check each test you need. Every state page on this site links to the official state list.
Is a mail-in kit informational or certified?
It depends on who runs the test. The word "kit" covers two different things:
- A lab's sample kit. Penn State's Agricultural Analytical Services Laboratory, accredited by the Pennsylvania DEP, sends a "Drinking Water Test Kit" with a cooler, sample bottles, instructions and a form. You collect the water and the accredited lab tests it. That gives a certified lab result.
- A kit you read at home, or one sent to an uncertified lab. SFPUC warns that even when a kit involves sending a sample to a laboratory, some products use labs that have not been certified. The Rhode Island Department of Health says store kits, and testing by companies that do not use a certified lab, may not give accurate results.
Before you buy a mail-in kit, ask which lab will test the sample, then look that lab up on your state's certification list for each test.
Test strips vs a certified lab, side by side
| Test strips or store kit | Certified lab | Certified lab with chain of custody | |
|---|---|---|---|
| Who runs the test | You, at home | A state-certified or accredited lab | A state-accredited lab, with professionals collecting the sample |
| What you get | A color band or a plus/minus line | A measured concentration on a lab report | A lab report plus a signed record of everyone who handled the sample |
| Good for | A quick first look, or watching for changes between lab tests | Health decisions, treatment choices, yearly testing | Documenting water quality before nearby drilling, mining or construction; some home sales |
| Accepted by law or a lender | No | Usually, if the lab is certified for each test (check the rule or lender) | Yes, where a third-party sample is required |
When do you need a certified lab result?
- Selling a home in Oregon: under ORS 448.271, the seller must have the well tested for arsenic, nitrate and total coliform bacteria after accepting an offer, and send the results to the buyer and the Oregon Health Authority within 90 days. The Oregon Health Authority says the samples must be tested by an accredited laboratory and the results are good for one year.
- Selling a home in Rhode Island: the Rhode Island Department of Health says state law requires any home with a private well to have its water tested before it is sold or transferred.
- Loans: FHA, VA and USDA loans can require a well water test. See FHA, VA and USDA well water test requirements and buying a house with a well.
- A legal record: Penn State Extension says "chain of custody" or "third-party" testing is used to legally document water quality before a nearby land use change such as gas drilling, mining or construction, and sometimes in real estate sales. Professionals collect the sample, and everyone who handles it is listed on the chain-of-custody form. Not every accredited lab offers this, so ask first.
- Health decisions: if you are deciding whether to drink the water, mix baby formula with it, or buy treatment, use a certified lab. See test before you buy a water filter.
When is a test strip enough?
A strip can help you notice a change, for example a nitrate strip between yearly lab tests. It is not a replacement for the yearly lab test EPA recommends for coliform bacteria, nitrate, total dissolved solids and pH. Many contaminants that matter for health, such as arsenic, PFAS or uranium, need lab equipment.
What if a strip or kit shows a problem?
Confirm it with a certified lab before you act. Southwest Nebraska Public Health Department says that if your strip shows a problem, "it's best to send your water to a certified lab," and SFPUC says a poor kit result should be confirmed by a lab using certified methods and quality control. If the certified result is over a health standard, EPA says to contact your health department for next steps and retest to confirm.
A good strip result doesn't clear the water either: it only covers the few things the strip measures.
Sources
- EPA: Certification programs and certified laboratories for drinking water (updated Aug 11, 2026)
- EPA: Protect your home's water
- San Francisco PUC: Home test kits
- Rhode Island Department of Health: Testing your well water
- Southwest Nebraska Public Health Department: Private well water
- Penn State Agricultural Analytical Services Lab: Drinking water testing
- Penn State Extension: Chain of custody water testing (updated May 29, 2025)
- Oregon Health Authority: Domestic Well Testing Act
- Oregon Revised Statutes chapter 448 (ORS 448.271)
Questions
Are well water test strips accurate?
They can give a rough first look. Southwest Nebraska Public Health Department says its nitrate strips are not as accurate as lab testing, and the San Francisco PUC says a kit result is an initial step, not a final result.
What is the difference between informational and certified water testing?
An informational test, like a strip or store kit, is for your own use. A certified test is run by a lab your state certifies for drinking water, using approved methods, and is the kind of result a law, lender or health department accepts.
Can I use a home test kit when selling a house with a well?
Not where a law sets the rule. Oregon requires the seller to test for arsenic, nitrate and total coliform bacteria at an accredited lab, and Rhode Island requires a well water test before a home is sold or transferred.
Is a mail-in water test kit certified?
Only if a certified lab runs the test. Ask which lab tests the sample and check it on your state's certification list for each test you order.
Free well water checklist
15 family-friendly steps based on CDC and EPA guidance. Print it, keep it on the fridge, and know when to call a certified lab.
More guides
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- How Much Does Well Water Testing Cost? Real Lab PricesReal published prices from public labs, free programs, and the EPA-approved-lab myth.
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