Bacteria and coliform testing
The US Environmental Protection Agency recommends annual private-well testing for total coliform bacteria, nitrates, total dissolved solids, and pH. Contact a state-certified drinking-water laboratory and confirm its current scope and sample instructions.
Water Testing Finder lists 2,010 laboratory records across 22 certifying states. These are database counts, not a claim that every currently certified laboratory nationwide is listed.
Labs for home testing: 1,599. Commercial and industrial: 295. Plant and utility: 116.
Water Testing Finder lists laboratories from official state certification records. Certification alone does not establish that a laboratory currently tests for a particular bacteria category or accepts residential samples. Confirm its current test scope, sample acceptance, collection instructions, and fees with the laboratory.
Frequently asked questions
What does the US Environmental Protection Agency recommend for private-well testing?
It recommends annual testing for total coliform bacteria, nitrates, total dissolved solids, and pH. If you suspect other contaminants, the agency advises testing for those as well. These are agency recommendations, not a statement of state-specific legal requirements.
How do I find a laboratory?
Choose a state and review the laboratory’s certification record. Ask whether its current scope covers the test you need and request its sample instructions.
Does certification show that a laboratory accepts private residential samples?
No. Confirm acceptance and sample instructions directly with the laboratory.
Related pages
- Bacteria in well water
- Browse laboratories by certifying state
- Glossary: state-certified drinking-water laboratory
- Glossary: total coliform bacteria
- Glossary: analyte or test scope
Sources
- US Environmental Protection Agency, “Contact Information for Certification Programs and Certified Laboratories for Drinking Water”: https://www.epa.gov/dwlabcert/contact-information-certification-programs-and-certified-laboratories-drinking-water (accessed October 19, 2026).
- US Environmental Protection Agency, “Protect Your Home’s Water,” “Testing wells to safeguard your water”: https://www.epa.gov/privatewells/protect-your-homes-water (last updated February 26, 2026; accessed October 19, 2026).
- The annual testing recommendations above apply to private wells. They are not presented as state-specific legal requirements.