A search for water testing near you usually turns up dozens of companies claiming to offer laboratory testing, but not all of them are running a lab of their own. The best water testing laboratory is the one that holds the right accreditation for your testing needs and runs that testing under a reliable quality system. 

In this article, we’ll walk through how to tell the difference, starting with what kind of testing you need.

Where Is the Best Place to Get Your Water Tested?

The best place to get your water tested is an accredited laboratory that can handle your specific testing needs, whether that lab is nearby or reached entirely by mail. Many accredited laboratories accept properly collected samples through the mail, which means you can work directly with a qualified laboratory no matter where you live.

Local drop-off can be convenient, but mail-in testing puts your sample in front of the same lab equipment and the same scientists either way. Turnaround time begins from the date your sample arrives at the laboratory, not from the date you ship it. That’s true whether you drive it across town or mail it across the country.

Laboratory quality and accreditation count for more than proximity, and so does transparency. 

A lab that’s physically closer doesn’t give you a better result if it isn’t the one running your test.

Do You Need Compliance Testing or Informational Testing?

Most people searching for a water lab don’t realize there are two different categories of testing, and knowing which one applies changes what you should look for in a laboratory:

Compliance Testing

Compliance testing exists to satisfy a regulatory requirement:

• Required under the Safe Drinking Water Act
• Used primarily by public water systems
• Reported to state or federal regulators
• Often requires a state-certified laboratory
• Sometimes required for specific legal or real estate transactions

Informational Testing

Informational testing serves a different purpose. Homeowners use it, and so do private well owners and city water customers who want a better picture of what’s in their supply. 

Note: Because informational testing isn’t submitted to regulators, homeowners on private wells are generally not required to use a state-certified laboratory. Choosing an accredited laboratory remains the best way to ensure accurate, reliable results.

What Should You Look for in a Water Testing Laboratory?

Once you know which type of testing you need, the next step is evaluating whether a laboratory is qualified to perform it.

ISO/IEC 17025 Accreditation

ISO is an international organization that develops standards used across many industries to promote consistency and quality, and ISO/IEC 17025, specifically, is an internationally recognized standard for laboratory quality. Accreditation to this standard evaluates:

• Technical competence
• Equipment calibration
• Staff qualifications
• Quality management systems
• During proficiency testing, laboratories receive samples with unknown contaminant levels and must accurately identify them without knowing the correct answers beforehand.
• Consistent, reliable reporting

Accreditation bodies audit a laboratory’s full quality system on an ongoing basis, which separates an accredited laboratory from one that simply advertises good service.

State Certification

State certification is a separate credential, managed individually by each state, and it’s required for many types of compliance testing. There’s no single national program, so requirements and oversight vary from one state to the next. Some state programs are well funded and re-inspect labs annually, while others are stretched thin and may only manage a re-inspection every few years. State certification is also scoped narrowly to whether a lab can correctly perform specific approved methods, not the lab’s broader business practices or overall quality culture. None of this is a knock against state programs, which serve an essential regulatory function. It’s simply useful context, since state certification isn’t always necessary for informational testing done at a homeowner’s request.

Note: State-certified laboratories also participate in proficiency testing, but ISO/IEC 17025 accreditation adds broader quality system requirements and ongoing independent assessments.

Why “EPA-Certified Laboratory” Can Be Misleading

Some companies do advertise themselves as an EPA-certified laboratory or offering EPA-certified testing, and it’s one of the more common inaccuracies in lab marketing. 

Outside a narrow federal program, that claim usually isn’t true, and it tells you something useful: how carefully a company describes itself in general.

The EPA develops and approves testing methods, and states generally handle laboratory certification. Independent accrediting organizations, separate from any government agency, evaluate laboratories against standards like ISO/IEC 17025. The EPA generally does not certify laboratories for routine drinking water testing, aside from a narrow exception under the Unregulated Contaminant Monitoring Rule.

A company that gets its own credentials wrong, whether from carelessness or an attempt to sound more official, is a reasonable prompt to look closer before trusting it with your water sample.

Why Does It Matter Whether a Company Has Its Own Laboratory?

Many companies that sell water testing kits don’t perform the analysis themselves. They collect your payment, provide you with a sample kit, then route it into a network of partner labs, sometimes hundreds of them, and the sample gets tested wherever it lands that week. The company selling the kit is mostly checking whether results come back on time. It isn’t auditing every lab in that network on an ongoing basis.

The Benefits of Testing Directly With a Laboratory

When you work directly with the laboratory doing the analysis, several things change:

• You know exactly where your sample is tested
• You know who generated the report
• You can communicate directly with the people who ran the test
• Your results come from one consistent quality system, start to finish

Accredited and state-certified laboratories are required to disclose, on the report itself, whether each result was generated using a method within their accredited or certified scope. In practice, that often shows up as a notation next to each analyte tested, confirming the method was covered or flagging that it fell outside the lab’s scope.

That requirement is tied directly to the lab holding the accreditation or certification. A reseller that sells a kit and forwards your sample doesn’t hold that credential itself, so it isn’t bound by the same disclosure obligation. It’s simply relaying whatever numbers come back from whichever lab handled your sample, with no outside authority holding the reseller to that reporting standard the way there is for the lab that did the work.

Going directly to a laboratory that holds its own accreditation or certification is the deciding factor, whether that’s ETR Laboratories or another lab entirely, so the transparency and reporting standards described above apply to whichever company you’re working with.

Where Does ETR Laboratories Fit In?

ETR Laboratories has performed water testing in-house for more than 30 years, with a laboratory primarily located in Leominster, Massachusetts. Every sample is tested on-site by ETR’s own scientists, and ETR Laboratories is accredited to the ISO/IEC 17025 standard through ANAB, the ANSI National Accreditation Board, one of several organizations that accredit laboratories against that standard, for the applicable testing listed on its scope. And because ETR Laboratories holds its own accreditation, it’s directly accountable for the quality, transparency, and reporting of every result it issues.

ETR is available nationwide through mail-in testing, so a search for water testing nearby can lead to a qualified laboratory anywhere in the country. If something about a result doesn’t look right, ETR’s policy is to retest at no charge.

Find Water Testing Services Near You

While ETR Laboratories accepts water samples from anywhere in the country through its nationwide mail-in testing service, we also offer location-specific resources covering common water quality concerns in select areas, such as:

Detroit Water Testing

Detroit’s aging water infrastructure presents unique challenges for homeowners. The city still has more than 80,000 lead service lines, many serving homes built before 1945, and aging water mains increase the risk of contamination entering the distribution system after breaks or repairs. Since lead has no taste, smell, or color, laboratory testing is the only reliable way to know what’s reaching your tap. Learn more on our Detroit Water Testing page.

Dallas Water Testing

Recent testing has detected PFAS compounds in parts of Dallas’s drinking water, including PFOA and PFOS above the EPA’s 2024 federal limits at one treatment plant. While legal and regulatory responses continue, laboratory testing allows homeowners to understand the water quality at their own tap today. Visit our Dallas Water Testing page to learn more about local testing considerations.

Houston Water Testing

Houston’s drinking water contains detectable levels of contaminants such as arsenic, trihalomethanes (TTHMs), haloacetic acids (HAA5), and several unregulated contaminants currently under EPA review, including PFAS and lithium. Although these levels remain within federal standards, some exceed more protective health-based guidelines published by independent organizations. Learn more about regional water quality on our Houston Water Testing page.

San Antonio Water Testing

San Antonio’s water comes from multiple aquifers and surface water sources, each with its own water quality considerations. Local concerns include elevated brominated trihalomethanes formed during disinfection, as well as nitrates and chromium-6 that have been detected in the region. Household testing provides the clearest picture of what is actually coming from your tap. Learn more on our San Antonio Water Testing page.

If you don’t see your city listed, you can still send your water sample to ETR Laboratories from anywhere in the United States. If you’re unsure which test best fits your water source or concerns, contact us for a free consultation. We’ll help you choose the right test before you place your order, and because every sample is analyzed in our own accredited laboratory, you’ll know exactly where your water is tested and who stands behind your results.

Frequently Asked Questions 

Can I mail my water sample to a laboratory?

Yes. Many accredited laboratories, including ETR Laboratories, accept properly collected samples through the mail. Turnaround begins once the sample arrives at the laboratory.

Does the EPA certify water testing laboratories?

Generally, no. The EPA develops and approves testing methods, and states typically handle laboratory certification. Independent accrediting organizations evaluate laboratories against standards like ISO/IEC 17025, with a narrow exception for testing under the Unregulated Contaminant Monitoring Rule.

Does the EPA test drinking water directly?

No. The EPA doesn’t test residential or commercial drinking water itself. If you want your water tested, contact a state-certified or accredited private laboratory directly.

What’s the difference between a certified and an accredited laboratory?

Certification is usually issued by a state and tied to specific compliance testing requirements. Accreditation, such as ISO/IEC 17025, is issued by an independent organization and evaluates a laboratory’s entire quality system, including staff competency, equipment calibration, documentation, and reporting practices.

How long does water testing take?

Turnaround time varies by laboratory and by test, and the clock starts the day your sample arrives at the laboratory.

Do private well owners need a state-certified laboratory?

Usually not. Private well owners typically need informational testing. That type of testing doesn’t require the state certification tied to regulatory compliance, so an accredited laboratory is an appropriate choice.

What should I test my water for?

That depends on your water source and any local concerns. Private wells often call for a broader baseline panel, while city water customers may focus on specific issues like lead, taste, or hardness.

How much does water testing cost?

Cost varies by provider and by how many contaminants a panel covers, with basic screenings costing less than a comprehensive panel that checks for metals, PFAS, and bacteria. 

How often should I test my water?

Private well owners are generally advised to test annually for bacteria and nitrates, with additional tests if there’s a known local concern. City water customers can test less frequently, though it’s a good idea to check again after any noticeable change in taste, color, or odor.

What are the signs of contaminated or poor-quality water?

Cloudiness, an unusual odor, a metallic or chemical taste, staining on fixtures, and skin or eye irritation after use can all point to a water quality issue. Many contaminants that carry the most serious health risks, including lead and certain bacteria, have no taste, smell, or color at all, so testing is the only reliable way to know what’s in your water.

Can contaminated water cause health problems?

Some contaminants, including certain bacteria, nitrates, and heavy metals, carry health risks ranging from gastrointestinal illness to longer-term concerns depending on exposure level. If you suspect your water is making someone in your home sick, contact your doctor and have your water tested, since symptoms alone can’t tell you what’s in it.

Does the health department offer free water testing?

Some local health departments offer basic testing, often limited to bacteria or a narrow set of parameters, particularly for private well owners. Availability and scope vary by location, so check with your local health department directly to see what they cover.

What are the basic tests used to check water quality?

Basic water quality checks often look at physical characteristics like color, odor, taste, turbidity, and temperature. These can flag an obvious problem, but they don’t detect most dissolved contaminants, which require laboratory analysis to identify accurately.