Most buyers assume the scary part of a well-and-septic purchase happens during the inspection period, when someone runs a camera down a pipe or checks a leach field for standing water. In Cortlandt Manor, that is not where the real deadline sits. The clock that actually matters starts the moment both parties sign the contract of sale, and it runs whether or not anyone remembers it exists.

Westchester County has required well water testing at the point of sale since November 2007, under a local law that applies to any property served by a private well. The seller has ten days from contract signing to order the test. The seller pays for it, typically $400 to $450. And the sample cannot be collected by the homeowner, the real estate agent, or a mail-in kit purchased online. It has to come from an employee or authorized representative of a New York State certified laboratory, full stop. Miss that detail and you can burn through the ten-day window with a test result the county will not accept.

Cortlandt Manor is exactly the kind of place where this law does its heaviest lifting, and understanding why also explains something odd about the neighborhood's home prices.

The Two Cortlandt Manors

Cortlandt Manor is an unincorporated hamlet in the Town of Cortlandt, not a village with its own municipal water district. Westchester County's own planning department notes that septic systems are more common in the county's northern communities, and Cortlandt Manor sits squarely in that northern band.

That geography produced two distinct housing stocks living under one hamlet name. One is the postwar wave of capes and ranches, many built between the 1940s and 1960s on smaller lots nearer the hamlet's commercial center, plenty of which tie into public water and sewer. The other is the wooded, larger-acreage parcel further out, often built later or extensively renovated, sitting on a private well and a septic field because no public line ever reached that far. Same hamlet, completely different closing paperwork.

If you are touring homes here without asking which side of that line each one sits on, you are shopping two different markets and treating them as one.

The Ten-Day Clock, In the Order It Actually Runs

Here is what the Westchester County Private Well-Water Testing Law actually requires, step by step, once a buyer and seller sign:

1. The seller has ten days from the date the contract is executed to order the test from a lab certified by New York State.
2. The certified lab, not the seller and not the buyer's agent, physically collects the water sample.
3. The lab tests for a required list of contaminants, including total coliform bacteria, nitrate, arsenic, lead, iron, manganese, sodium, chloride, and a set of organic contaminants and MTBE.
4. Results go to the Westchester County Department of Health directly from the lab.
5. The seller must also get those results to the buyer, generally within five days of receiving them.
6. Neither side can waive the requirement by agreement. It happens regardless of what the contract says.

The law also covers new wells and any well that has sat unused for five years or more, and it extends to leased properties on an ongoing basis, not just sales. If you are a Cortlandt Manor landlord with a well-supplied rental, this is not a one-time hurdle you clear and forget.

The county's own health department frames the requirement plainly: it exists to confirm that private well systems meet drinking water standards before a transaction closes, with no carve-out for a quick handshake waiver between a motivated buyer and seller.

Three Counties, Three Different Clocks

Because Nicole works across Westchester, Rockland, and Putnam, the county line matters more than most buyers expect. Rockland's law tracks Westchester closely. Suffolk County runs the opposite direction entirely.

A buyer who has shopped in Suffolk before and assumes they can waive the test to speed things up will be surprised in Cortlandt Manor. There is no version of this contract where that shortcut exists.

Septic Doesn't Get the Same Clock

Here is the part that trips people up in the other direction. Buyers who learn about the mandatory well test sometimes assume the septic system gets the same legal treatment. It does not.

Westchester's sanitary code requires county health department review and approval for new construction, teardowns rebuilt to the foundation, and additions that add bedrooms or new rooms with bathroom access. It does not compel a septic inspection simply because a home changes hands. Attorneys who handle Westchester closings routinely list a septic evaluation as something the purchaser typically arranges through a home inspector or septic specialist, as a matter of practice rather than a legal requirement tied to the sale itself.

That distinction matters for negotiation. The well test is not optional and not negotiable. The septic inspection is a smart move that a buyer has to request and pay for on their own initiative, and a seller who wants a clean, fast close in this hamlet should consider getting ahead of it before the home ever hits the market. Worth noting: the county even runs a free repair program for failing septic systems within the New York City watershed, which tells you how seriously it takes system health even where it has chosen not to mandate an inspection.

Why the Median Price Swings by $400,000 in a Single Month

This is where the well-and-septic line stops being a paperwork detail and starts explaining the market itself.

The most recent Zillow estimate puts the typical home value in the 10567 zip code at $548,805, down slightly over the past year. Redfin's snapshot for March 2026 told a completely different story: a median sale price of $950,000, a number that looked wildly out of step until you noticed the sample behind it. That figure came from exactly one closed sale that month, down from five sales in March of the year before.

That is not a data error. Cortlandt Manor does not have its own MLS boundary the way an incorporated village does, so a single month's resale figures come from whichever handful of homes happened to close, drawn from either side of the well-and-septic line. A month where the closings skew toward the larger wooded parcels on private systems will report a median that looks nothing like a month dominated by the smaller postwar homes near the commercial strip.

If you are pricing a listing or sizing up a purchase based on a headline median you saw on a portal, ask which kind of home actually closed that month before you trust the number. And if the property you are eyeing sits on the well-and-septic side of that line, build the ten-day clock into your offer strategy now rather than discovering it after you have already signed.

Buying or selling a well-and-septic home in Cortlandt Manor is not harder than any other Westchester transaction. It just runs on a different calendar, and the sellers and buyers who know the calendar in advance are the ones who close on schedule. If you want to walk through what that timeline looks like for a specific address, Nicole Biello offers a free strategy call built around exactly this kind of local mechanics.

FAQ

Does the Westchester well test apply if I'm renting out a property instead of selling it? Yes. The law requires ongoing testing for leased properties supplied by a private well, not only for outright sales.

Can I use a water test I already had done a few months ago? Only if a certified lab performed it under the law's specific collection rules and it falls within the required window tied to your contract date. A routine test you arranged yourself for peace of mind generally will not satisfy the county requirement, so budget for a fresh one once you are under contract.

What happens if the well fails the test? A failed result for a primary contaminant is not automatically a dealbreaker. New York allows for remediation and treatment, and the responsibility for addressing it is typically spelled out in the contract rather than falling on the buyer by default.