Last checked: October 23, 2026

Well water testing in Westchester County, New York

Westchester is one of the few places in New York that requires a well water test when a home is sold. The county's Private Well Water Testing Law also covers rentals and new wells. Here's what it requires, who may collect the sample, which labs are registered with the county, and where to get help. Every fact has a source.

How many people here use a private well

USGS estimates that about 43,000 people in Westchester County supplied their own household water in 2015, about 4% of the county's population.¹ Most of the county is on public water, so if you're buying in a well area, check what the house actually has.

The Private Well Water Testing Law

Westchester County Local Law 7 of 2007 (Laws of Westchester County Chapter 707) was adopted on May 23, 2007, and took effect on November 19, 2007.² It applies to properties served by private wells used for drinking water. It doesn't apply to property served by a regulated public water supply, to gifts of property, or to transfers by operation of law.³

When a test is required:³

• Sale: when a contract of sale is signed, the seller must have the well water tested. The results go to both buyer and seller.
• Rentals: a landlord must test, then test again at least every five years, give the results to current tenants within 5 days of receiving them, and give a copy of the latest results to each new tenant.
• New wells must be tested before first use, and a well that hasn't been used for five years is treated as a new well.
• A well used only for something like lawn watering, at a property that drinks public water, doesn't have to be tested.

If the sale goes ahead without a test, the county says the sale may not be void, but the parties may face enforcement action by the Department of Health.³

What must be tested

Every well must be tested for:³

Lead needs two samples: a first-draw sample (one liter from a cold tap after the water has sat in the pipes for at least six hours, without flushing) and a flushed sample (after running the cold tap at least two minutes, or until the water turns cold, whichever is later).³

If a result fails: treatment is required only when a primary contaminant still doesn't meet the standard after any other fixes. Failing only a secondary contaminant doesn't require treatment. A well that already has treatment still has to be tested.³ The county's Rules and Regulations (Section 3 and Appendix A) set out the remediation steps.³

Who collects the sample, and who pays

• The sample must be collected by an employee or authorized representative of a lab certified by the New York State Department of Health. You can't collect it yourself, and a real estate agent can't either, unless the agent is a certified lab's employee or authorized representative.³
• Untreated water. A softener, filter or other treatment unit must be bypassed or disabled, or the sample taken before the water goes through it.³
• More than one lab can do the tests, but each must be certified for what it tests, the person collecting must be from a lab registered with the county, and one lab must send all the results to the county electronically.³
• How long results count: results collected under the law can be used for one year, except coliform results, which are good for six months. Results from an old well don't count for a new one.³
• Who pays: on a sale, the seller pays for the required tests; extra tests are negotiated between buyer and seller. On a rental, the landlord pays.³ The county's FAQ gives an average price estimate, but it dates from when the law took effect, so ask labs for current prices.

Labs registered with the county

The county keeps a list of New York State certified labs registered with the Department of Health to submit test results under the law. The current list (2025) includes:⁴

The county says the list may change and that it doesn't endorse any lab.⁴ Neither do we. Confirm a lab's certification for each test in NYSDOH's ELAP directory.⁶

Buying a home with a well in Westchester County

• The seller tests once the contract is signed, and both sides get the results.³ Ask for the full lab report, not just a pass/fail summary, and check the sample date against the one-year (six months for coliform) window.
• State disclosure: New York's Property Condition Disclosure Statement asks the seller what the water source is and whether the water quality or flow rate has been tested.⁵
• The law covers water quality, not quantity. The required list above has no flow or yield test, so ask for one separately. Our homebuyer's guide covers flow tests, contingencies and what to ask the seller.
• Realtors and home inspectors: see our guides for realtors and home inspectors.

Free PFAS testing

Westchester is one of six counties in the New York State Department of Health's Private Well PFAS Testing and Mitigation Rebate Pilot Program, which offers limited free private well testing for PFAS. Rebates for treatment (or connecting to public water) are available only if PFOA or PFOS is at or above 10 ng/L and the well was tested through the program. The state says it may pause applications as it tracks funds, so check the program page.⁷

What to test when you're not selling

NYSDOH recommends testing for bacteria every year, and every 3–5 years for lead, nitrate/nitrite, arsenic, sodium, iron/manganese, turbidity, pH, hardness and alkalinity.⁶

Contacts

• Westchester County Department of Health, private well water: 914-995-7268. The private well water page links the law, the rules and regulations, the Q&A and the lab list.²
• Well records: New York's well completion reports are in NYSDEC's DECinfo Locator.⁸
• Statewide: see Private wells in New York.

Where to get tested and treatment options

Related guides

• Buying a home with a well
• Private wells in New York
• Dutchess County, NY
• How to read your well water test results