Last checked: October 22, 2026

Who regulates private wells?

Short answer: for the water itself, mostly nobody but you. Federal drinking water standards apply to public water systems, not to a well serving one home. States and counties often regulate how a well is built and who may build it, and a few require testing when a home is sold. Day to day, testing and upkeep are the owner's job. Here's how the layers fit together.

The owner: responsible for the water

EPA says private well owners are responsible for their own drinking water, and that the quality of water from private domestic wells isn't regulated by the federal government under the Safe Drinking Water Act, or by most state governments.¹ USGS likewise says the quality of self-supplied water is not directly regulated by federal or local laws.²

In practice that means the owner decides:

• When and what to test. EPA recommends testing every year for total coliform bacteria, nitrates, total dissolved solids and pH, and testing right away after changes like flooding, repairs or a change in taste, odor or color.³ See how often to test.
• Which lab to use. EPA recommends only labs certified for drinking water testing, which you can find through your state's lab certification program or your local health department.³
• Whether to treat, repair or shock the well. See shock chlorinating a well and whole-house vs point-of-use treatment.

The federal government: standards for public systems

The Safe Drinking Water Act (1974, amended in 1986 and 1996) lets EPA set national health-based drinking water standards, which EPA, states and water systems work together to meet. EPA says SDWA does not regulate private wells that serve fewer than 25 individuals.⁴

A system counts as a public water system if it pipes water for human consumption to at least 15 service connections, or serves an average of at least 25 people at least 60 days a year. It can be publicly or privately owned.⁵ So a well shared by a small subdivision or serving a business may be regulated as a public system even though a single home's well isn't. Ask your state drinking water program if you're not sure which applies.

What the federal government does offer private well owners:

• Benchmarks. EPA's public-water limits don't legally apply to your well, but they're often used as a yardstick for well results (HUD uses them for FHA loans, below). Our results checker shows them next to your numbers.
• Information and help. EPA funds the Private Well Class's Private Well Help Center, run by the Rural Community Assistance Partnership and the Illinois State Water Survey at the University of Illinois. Its toll-free hotline is 1-866-945-0699 (8:30 a.m.–4:30 p.m. Central, Monday–Friday), with 24/7 online chat.⁶ EPA itself says it can't test residential water on request.⁷
• Home loans. For FHA loans, HUD guidance says individual wells don't need automatic testing unless the state or locality requires it, contamination is suspected, or the water depends on a purification system. Where testing is required and there's no local standard, EPA's limits apply.⁸

States: construction, licensing, and sometimes testing

EPA says most states have zero or limited regulations for private drinking water wells, but that states do have programs to help well owners.⁹ USGS says well drilling requires licensure and permits in most states.² What states commonly cover:

• Well construction standards such as casing, grout and setback distances. EPA notes that some states and local agencies set minimum casing lengths.¹⁰ The Water Systems Council, a well-industry nonprofit, keeps a searchable State Well Codes database of state construction and siting standards. It says the database is a guide and standards change, so check with the state.¹¹
• Licensing of drillers and pump installers. EPA recommends using contractors who are licensed and certified where your state requires it.¹⁰
• Well records. Many states keep databases of well logs. Minnesota's statewide well rules, for example, date from 1974.¹²
• Testing or disclosure when a home is sold, in a few states:
• New Jersey's Private Well Testing Act requires testing at sale for a list of up to 43 parameters.¹³
• Oregon requires the seller to test for arsenic, nitrate and total coliform after accepting an offer, and to report results to the buyer and the Oregon Health Authority.¹⁴
• Rhode Island requires purchase contracts for homes on wells to give the buyer a testing period.¹⁵
• Minnesota requires sellers to disclose all known wells, without requiring a water test.¹⁶¹²
• Wisconsin doesn't require an inspection at sale, but anyone paid to inspect a well at a property transfer must be a licensed well driller or pump installer.¹⁷

Our buying guide's state table covers more states.

Counties and towns: permits and local rules

Some counties and towns add rules of their own, so check locally even if your state has none. Examples we've verified include Westchester County, New York, which requires well testing at sale, and Dakota County, Minnesota, which requires testing at property transfer.¹⁸¹² EPA suggests contacting your local health department to learn which contaminants are common in your area, and notes it may test private wells for free.³

How to find your state's private well program

1. Start with EPA's directory. EPA's Private Drinking Water Well Programs in Your State links to each state's program.⁹
2. Check your state page here. Each of our state pages lists the state agency, the home-sale rule, the well-log database, certified-lab lookups and local contacts we found.
3. Call your county or local health department for permits, local testing rules and any free or low-cost testing.
4. Look up the construction code in the Water Systems Council's State Well Codes database, then confirm with the state agency.¹¹
5. Still stuck? Call the Private Well Help Center at 1-866-945-0699.⁶

Related guides

• Why do so many U.S. households use private wells?
• How a private well works
• Private well vs city water: pros, cons and costs
• Buying a home with a well
• How often should you test a private well?