If you’re selling a Westchester home that gets its drinking water from a private well, county law requires a well water test. If the home has a septic system, there is no county requirement to inspect it because you’re selling.
Wells. Since November 19, 2007, the seller must order and pay for a lab test of the well water when the contract is signed, and give the buyer the results. If a health-related result fails and fails again on a retest, the law gives three options: the seller fixes the problem, the seller cancels the sale and returns the deposit, or the buyer agrees in writing to close and fix it.
Septic systems. The rules that apply are not tied to a sale. Several towns in the New York City watershed require owners to have their septic tank pumped out every five years. Any repair needs county approval, and a buyer can ask the county for the system’s records.
The well law applies in every city, town and village in Westchester. For Long Island, where neither county has a sale rule for wells or cesspools, see cesspool and septic rules on Long Island.
Where wells and septic systems are common
Mostly in the northern towns. Pound Ridge has no public water system, so homes there rely on private wells, according to the town’s Conservation Board (Town of Pound Ridge, Water Testing). A 2016 county planning study found that 90% of North Castle residents get water from drilled wells (North Castle base study).
For septic systems, the county’s watershed loan program is a useful guide. It covers Bedford, Cortlandt, Harrison, Lewisboro, Mount Pleasant, New Castle, North Castle, North Salem, Pound Ridge, Somers, Yorktown, and the Village and Town of Mount Kisco. The county puts the number of septic systems in that part of the New York City watershed at about 27,000 (Westchester County, Mar. 25, 2026). Many of those towns are partly on sewers or public water, so each lot has to be checked.
The well water testing law
The county’s Private Well Water Testing Law and the Health Department’s rules apply to the sale of any property whose drinking water comes from a private well. They do not apply to gifts or to transfers that happen automatically by law. They also don’t apply to water systems with five or more connections, or that regularly serve at least 25 people a day for 60 days a year.
What the seller must do, and when
| Step | Deadline |
|---|---|
| Order the test | When the contract is signed |
| Confirm to the buyer that it was ordered | Within 10 days |
| Give the buyer the lab report | Within 5 days of getting it |
| Buyer and seller each sign that they reviewed it | After review |
The seller arranges and pays for the test. The county’s Q&A estimates the average cost at $400 to $450 (County Q&A). The Q&A is undated, and lab prices vary.
A recent test can be reused. Results are good for one year from when the sample was taken, or six months for coliform bacteria. If the contract is signed inside that window, no new test is needed, as long as the seller gives the results to the buyer and the Department of Health within 10 days of signing. Either side can retest, and the buyer can test for more than the required list.
Who takes the sample and what is tested
Only an employee or authorized representative of a lab certified by the New York State Department of Health may take the sample. A real estate agent can’t, unless the agent is that lab’s representative. The rules require representatives to have no stake in the property or the sale.
The sample must be untreated water, taken before any filter or softener or with treatment bypassed. Lead needs two samples: one from the first water drawn and one after flushing (County Q&A). The lab sends results electronically to the County Department of Health as well as to whoever ordered the test.
| Primary (health) items | Secondary items |
|---|---|
| Total coliform | pH |
| E. coli or fecal coliform (if coliform positive) | Iron |
| Nitrate | Manganese |
| Arsenic | Sodium |
| Lead | Chloride |
| Part 5 organic contaminants | |
| Vinyl chloride | |
| MTBE |
Sources: County Q&A; law summary. “Part 5” means the main organic chemicals listed in Part 5 of the New York State Sanitary Code.
Only a failed primary item triggers the law’s fix-it rules. A secondary result, such as high iron or sodium, is reported but does not require treatment.
PFAS (“forever chemicals”) are not on the required list. Separately, a New York State pilot program announced for Westchester in May 2026 offers eligible well owners free PFAS testing. Where results meet or exceed state standards, it offers rebates of up to $5,000 for treatment or up to $10,000 for a public water connection (Westchester County, May 1, 2026).
If the well fails
If a primary item fails, a second sample for that item must be taken within 7 days of the result, from the same spot and under the same conditions. If it fails again, the law gives three options:
- The seller fixes the problem and the parties close.
- The seller cancels the contract and returns the down payment, and neither side owes the other anything.
- Buyer and seller agree in writing to close with the buyer fixing the problem.
A seller who chooses to fix it must do so within 60 days or as soon as practical. A buyer who takes it on has 60 days from closing. A fix can mean disinfecting the well, repairing it or installing treatment. The county says treatment is required only when a primary item still fails after other steps (County Q&A).
For the third option, the law requires only a written agreement. Whether the cost is handled by a lower price, a credit or money held back in escrow is up to the contract.
What the law does not do
A sale made without the test is not void. The county says people who break the law may face enforcement by the Department of Health (County Q&A). Fines run up to $1,000 per violation, and up to $10,000 for each failure to fix a problem that goes on more than a month. The law creates no lien, and nothing is recorded with the County Clerk, so a title search won’t show whether a test was done.
The law also requires landlords to test at least every five years, and new or long-unused wells to be tested before use.
Septic systems: no sale inspection, but other rules apply
County approval for repairs and new systems
The County Department of Health regulates septic systems under the county sanitary code and its design rules for home septic systems (onsite wastewater treatment systems, or OWTS) and wells, in effect since April 1, 2022 (County DOH, Septic Systems; design rules).
- A new or rebuilt system needs a permit and approved plans before work starts, and a Certificate of Construction Compliance before it is used.
- A repair, even a like-for-like replacement, needs the Department’s written approval before a licensed contractor does the work. Emergencies have a faster process (see the professional section).
- A system that has already been repaired once can’t simply be repaired again; the next fix is treated as a rebuild, with a site evaluation and plans.
- An addition or other change that the local building department refers to the county needs the Department to confirm the existing system is adequate.
Five-year pump-out laws in watershed towns
The repeating requirement is on a schedule, not tied to a sale. In 2011, towns in the part of the New York City watershed east of the Hudson passed local laws requiring each septic system to be inspected, meaning pumped out by a county-licensed septic hauler, at least once every five years. The laws carried out a requirement in the state’s stormwater permit for municipalities (the MS4 permit). Examples:
- Pound Ridge (2011): at least every five years from May 1, 2011; the owner keeps the hauler’s record for six years; $500 fine after a 30-day notice (Pound Ridge law).
- Yorktown (2011): once every five years; record kept six years; $200 per violation (Yorktown Code).
- North Castle (2011, fines changed in 2020): fines up to $1,000 per day after a 30-day notice (North Castle Code).
- North Salem (2011): at least every five years from May 1, 2011; $200 per violation after a 30-day notice (North Salem Code).
- Bedford passed a five-year pump-out law in 2011 covering about 6,300 systems (Patch, Mar. 2, 2011; NYS septic inspection programs). Lewisboro describes the same five-year rule (Lewisboro CAC).
None of these laws makes a sale depend on a pump-out. The owner keeps the record; it is not filed as a lien. At a sale, the question is whether the seller can produce it.
New York City watershed rules
New York City’s watershed rules also cover septic systems in the watershed east of the Hudson. In Westchester, that includes the Croton system and the Kensico basin. The County Department of Health reviews septic applications for the City’s Department of Environmental Protection (DEP). The rules limit where new systems can go, such as no leach field within 100 feet of a stream or mapped wetland or 300 feet of a reservoir. Changing a system or fixing a failed one needs approval. An existing system that doesn’t meet current rules can keep operating, but one unused for five years in a row needs DEP permission before it is used again (DEP guide to septic systems).
Help paying for a failing system:
- DEP reimbursement: for systems built before 1997 that serve a primary one- or two-family home in priority areas (DEP program).
- County loans: interest-free, up to $49,999, for septic repair or a sewer connection in the watershed towns listed above (Westchester County, Mar. 25, 2026).
How buyers check a well or septic system
The disclosure statement. For one- to four-family homes, the Property Condition Disclosure Statement, the seller’s form describing the house, asks the water source (Question 34), whether water quality or flow has been tested (Question 35), and the type of sewage system (Question 36) (New York’s disclosure law). Exemptions and remedies are covered in selling inherited property in New York. The county well test is a separate duty and applies even when the disclosure statement does not.
County health records. The Department of Health keeps approved plans for septic systems and wells. You request them with the county’s records or sketch request form. Archived files can take up to 10 business days (County DOH, Septic Systems). An approved as-built plan shows where the system and well are. Older houses may have no file.
Septic inspection. No county rule sets what a pre-purchase septic inspection must cover, so the contract and the inspector decide. A report that only looks at the yard tells a buyer less than one that finds, uncovers and pumps the tank. Any repair it leads to needs county approval before the work.
Water flow and lender rules. The county test measures water quality, not how much water the well produces. No county law requires a flow test. A lender may set its own well or septic conditions. Those are loan conditions, separate from the county law.
Does a well or septic system affect title?
Usually not. Water quality and septic condition are about the property’s condition, not its ownership.
Municipal searches. The standard Westchester residential search package does not include a health department search (see Westchester municipal searches). Open building permits for septic work or an addition do show up on the building search (see open permits and COs in Westchester).
Title insurance. The owner’s policy does not cover loss from government regulations unless a notice of enforcement is recorded. A failed water test or a septic repair order is not a covered title risk (see what a New York title insurance policy covers).
Location. A well, leach field or septic line on a neighbor’s lot, or a shared well, raises questions about easements (rights to use part of someone else’s land) and encroachments (something built over a property line). A shared well with no recorded agreement is a title question. A survey shows these parts only if the surveyor locates them (see the survey exception).
Details for attorneys and title professionals
- The well law’s structure. The well law was passed by the county in 2007 and is now part of the county’s codified laws. The exact law and section numbers for each rule above are listed under Official sources.
- Emergency septic repairs. In an emergency, the Department can approve a repair by phone, with the form filed within two business days.
- Watershed delegation. The County Department of Health reviews septic applications in the watershed under a delegation agreement with DEP. The 100-foot and 300-foot limits apply to the absorption field of a new system.
Official sources
- Westchester County Local Law 7 of 2007, Chapter 707, Private Well Water Testing (scope and exclusions, § 707.02; seller duties and deadlines, § 707.03(A) and (B); three options on failure, § 707.03(C); extra testing, § 707.03(D); leases and new wells, §§ 707.04 and 707.05; time to correct, § 707.06(B)(1); sampler, § 707.07(C); reuse of results, § 707.08(A); penalties, § 707.12)
- Westchester County DOH, Private Well Water
- Westchester County DOH, Private Well Water Testing Rules and Regulations (confirmation sample, § 2.0; laboratory representatives, § 4.0)
- Westchester County DOH, Private Well Water Testing Law Q&A
- Westchester County DOH, Septic Systems (Westchester County Sanitary Code, Article VIII)
- Westchester County DOH, Residential OWTS and Well Rules (2022) (permits and certificate, §§ 1.0 and 3.0; repairs, § 10.0; one repair then remediation, §§ 10.0 A.6 and 11.0)
- Westchester County, Septic System Rehabilitation and Sewer Connection Program, Mar. 25, 2026
- Westchester County, Private Well PFAS Testing, May 1, 2026
- NYC DEP, Applicant’s Guide to Subsurface Sewage Treatment Systems (15 RCNY Chapter 18, § 18-38)
- NYC DEP, East of Hudson Septic System Rehabilitation Reimbursement Program
- NY Real Property Law § 462
- Town of Pound Ridge, Local Law 2 of 2011
- Town of Yorktown Code, septic inspection (Local Law 3 of 2011)
- Town of North Castle Code, septic maintenance (Local Law 2 of 2011, amended 2020)
- Town of North Salem Code, septic inspection (Local Law 1 of 2011)
- Westchester County Planning, North Castle Base Studies, ch. 9 (2016)