Certified Lab Directory
EPA-Certified Water Testing Labs by State
If you want to know exactly what's in your water — and get a result you can act on — you send a sample to a certified lab.
This directory covers 13 states and 453 labs today. We publish a state only after we've pulled its official certification list from the agency that runs the program and confirmed that source loads. Every lab on every page here traces back to a government list you can open yourself, and we show you the link. More states go up as each one gets verified.
What “certified” actually means. Under the Safe Drinking Water Act, labs that analyze drinking water compliance samples must be certified by the EPA or by the state (EPA). In practice, most states run their own certification programs: they verify that a lab uses EPA-approved test methods, passes proficiency tests at least once a year for each method and analyte, and holds up under periodic on-site audits. So “EPA-certified” usually means certified by your state under the EPA's drinking water lab certification program. Same standard, administered locally.
That certification matters because anyone can sell you a water test. A certified lab is the only version where someone has checked the lab's methods, tested its accuracy, and audited its work. The EPA's own guidance for well owners is blunt about it: “Only use laboratories that are certified to do drinking water testing.”
Pick your state below to see its labs and how its certification program works.
Browse certified labs by state
Don't see your state? It isn't up yet. We'd rather publish the states we've verified than fifty we haven't, so a state goes live here the week we confirm its official list — not before.
You don't have to wait on us, though. The EPA maintains contact information for every state's drinking water laboratory certification program, including a state-by-state PDF that links straight to the office running the program where you live. That's the same place we start. Your state or county health department is the other call worth making — the EPA notes that if your household is on a private well, you can contact your state program for guidance or go directly to a certified lab to have the well tested, and some local health departments test private wells for free.
Source: EPA, Contact Information for Certification Programs and Certified Laboratories for Drinking Water (epa.gov/dwlabcert) and EPA, Protect Your Home's Water (epa.gov/privatewells).
How to pick a lab from the list
Every lab on these pages holds current certification from the program that certifies drinking water labs where it operates — usually the state, and in Wyoming's case the EPA directly (we cite the source and the date we pulled it on every state page). Beyond that, a few practical filters:
- Test for the right things. For a private well, the EPA recommends testing every year for total coliform bacteria, nitrates, total dissolved solids, and pH. Call the lab and confirm it's certified for those specific tests — labs are certified method by method and analyte by analyte, not as a blanket.
- Ask about sample handling. Some tests (bacteria especially) have short windows between collection and analysis. A good lab will tell you exactly how to collect, store, and deliver the sample. Many mail you a collection kit.
- Closer is usually better. Shorter drive, fresher sample, easier re-test if something comes back high.
- Check with your local health department first. Some offer private well testing for free.
And if the lab's answers feel vague or salesy, call the next one on the list. A lab's job is numbers, not pitches.
Do you need a certified lab, or is a home test kit enough?
Honest answer: it depends on what question you're asking.
A home test kit is a screening tool. Our free kit measures hardness and total dissolved solids in about 60 seconds. Those two numbers tell you a lot about what your water is doing to your pipes, appliances, skin, and hair — and whether a filtration or softening conversation is even worth having.
A certified lab is for health questions and official answers. Bacteria, nitrates, lead, arsenic, PFAS — anything where the result affects whether you drink the water needs a certified lab. Same if you need documentation: a real-estate transaction, a new well, a dispute with anyone. Home strips can't do any of that, and we won't pretend ours can.
The two aren't competitors. Plenty of people start with the free strips, see a number that raises an eyebrow, and then send a sample to a certified lab to find out what's actually going on.
Start with the free 60-second screen.
We'll mail you a free test kit that measures hardness and TDS at your tap. No credit card, no home visit. If the numbers look off, this directory is where you go next.
Get My Free Test KitCommon questions
What does "EPA-certified" mean for a water testing lab?
Under the Safe Drinking Water Act, labs that analyze drinking water compliance samples must be certified by the EPA or by the state. To hold certification, a lab has to use EPA-approved analytical methods, successfully analyze proficiency-test samples at least annually for each method and analyte it's certified for, and pass periodic on-site audits. Most states run their own certification programs under the EPA framework, so "EPA-certified" usually means certified by your state's program. Source: EPA, Learn About Laboratory Certification for Drinking Water (epa.gov/dwlabcert).
Why isn't my state listed here?
This directory currently covers 13 states and 453 labs. We add a state only after pulling its official certification list from the agency that runs the program and confirming that source is live, so states go up as they're verified rather than all at once. If yours isn't here yet, the EPA publishes contact information for every state's drinking water laboratory certification program, including a state-by-state PDF that links to the program office in your state. Your state or county health department is also worth a call. Source: EPA, Contact Information for Certification Programs and Certified Laboratories for Drinking Water (epa.gov/dwlabcert).
How often should I test my well water?
The EPA recommends testing a private well every year for total coliform bacteria, nitrates, total dissolved solids, and pH. Test more often if small children, elderly adults, or someone pregnant or nursing lives in your home. Source: EPA, Protect Your Home's Water (epa.gov/privatewells).
When should I test my water immediately instead of waiting for the annual test?
The EPA says to test right away if there are known water problems in your area, if conditions near your well have changed (flooding, land disturbance, new construction or industrial activity), if you repair or replace any part of your well system, or if you notice a change in your water's taste, odor, or color. Source: EPA, Protect Your Home's Water (epa.gov/privatewells).
What should I ask a lab to test for?
Start with the EPA's annual basics for wells: total coliform bacteria, nitrates, total dissolved solids, and pH. Then add tests based on your situation — the EPA publishes a list of conditions and what to test for in each case. Examples: nearby intensive agriculture points to nitrate, nitrite, pesticides, and coliform bacteria; stained fixtures or laundry point to iron, copper, and manganese; scaly residue and soap that won't lather point to hardness. Your local health department can tell you what's common in your area's groundwater. Source: EPA, Protect Your Home's Water (epa.gov/privatewells).
Can't I just use a home test kit instead of a lab?
For screening, yes. Home kits (including our free one) are a fast way to check things like hardness and total dissolved solids. But for health-related contaminants — bacteria, nitrates, lead, arsenic — the EPA's guidance is to only use laboratories that are certified to do drinking water testing. Certified labs follow approved methods and are audited for accuracy; strips and home kits are not. Source: EPA, Protect Your Home's Water (epa.gov/privatewells).
What do I do if my lab results show a contaminant above EPA limits?
The EPA's recommendation: contact your public health department for specific steps, and have your well re-tested to confirm the contaminant's presence and concentration before making decisions. Depending on the contaminant, treatment such as disinfection, distillation, or filtration may remove it. Source: EPA, Protect Your Home's Water (epa.gov/privatewells). If a confirmed result points to treatment, we can price out options based on your report — see our quote page.
Already have lab results in hand?
If your report shows hardness, high TDS, or a contaminant above EPA limits, treatment can usually fix it. Tell us what the lab found and we'll put together a filtration estimate based on your actual numbers — not a guess.
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