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Indian Hill Subdivision

What EPA’s and New York’s records show in this utility’s water: nitrate, arsenic and other regulated chemicals; lead and copper; and violations since 2016, with the certification that handles each result.

Serves
320 people
Connections
80
Water source
Groundwater
Based in
Lewisboro (T), NY
County
Westchester
Owner
Private
The ZIP code it serves

10536

The short answer

2 results are above the health goal. The worst: Uranium, above the health goal. 7 health-based violations since 2016.

What handles it

What was found

Lead and copper: EPA SDWIS monitoring periods ending 2007 to 2028.

Uranium, total trihalomethanes (TTHM), nitrate, haloacetic acids (HAA5) and arsenic: New York’s yearly summaries per water system, 2020 to 2024, with EPA’s 2012 to 2019 file for earlier years.

Chromium (total) and fluoride: EPA’s compliance monitoring file, samples taken from Aug. 6, 2013 to Sept. 18, 2018. Newer results are in the utility’s annual water quality report.

Above the health goal2

Uranium

Comes from the source

Above the health goal

6.5ppb

Highest yearly average, 2020 to 2024

2024 average: 6.3 ppb

Averaged by year, the highest was 6.5 ppb, in 2020: below EPA’s legal limit of 30 ppb, but above its health goal of zero. Its highest single sample was 8.1 ppb. In 2024, the latest year on file, it averaged 6.3 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 12.6 ppb, in 2014.

What handles it

Lead

Comes from pipes, often your own

Above the health goal

2.0ppb

90th percentile, 2026 to 2028

In the latest period, 9 in 10 homes sampled were at or below 2.0 ppb, below EPA’s action level of 15 ppb. The action level drops to 10 ppb on Nov. 1, 2027. EPA’s health goal for lead is zero.

What handles it

Below EPA’s limits3

Total trihalomethanes (TTHM)

Forms or is added in treatment

Below EPA’s limits

26.3ppb

Highest yearly average, 2020 to 2024

2024 average: 18.3 ppb

Averaged by year, the highest was 26.3 ppb, in 2023, below EPA’s legal limit of 80 ppb. Its highest single sample was 82 ppb. In 2024, the latest year on file, it averaged 18.3 ppb. EPA recorded no violation for total trihalomethanes (TTHM) at this utility since 2020. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 20.3 ppb, in 2012.

What handles it

  • NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
  • NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”

Nitrate

Comes from the source

Below EPA’s limits

3.0ppm

Highest sample; found in 5 of 5

2024 average: 2.0 ppm

The highest sample, in 2020, was 3.0 ppm, below EPA’s legal limit of 10 ppm. In 2024, the latest year on file, it averaged 2.0 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 2.4 ppm, in 2017.

What handles it

  • NSF/ANSI 58 look for “Nitrate/Nitrite Reduction”
  • NSF/ANSI 53 look for “Nitrate/Nitrite (30 ppm challenge)”

Haloacetic acids (HAA5)

Forms or is added in treatment

Below EPA’s limits

11.8ppb

Highest yearly average, 2020 to 2024

2024 average: 4.5 ppb

Averaged by year, the highest was 11.8 ppb, in 2023, below EPA’s legal limit of 60 ppb. Its highest single sample was 34 ppb. In 2024, the latest year on file, it averaged 4.5 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 3.4 ppb, in 2012.

What handles it

No certification claim covers this compound yet.

3 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
  • Arsenic
  • Chromium (total)
  • Fluoride

What handles it

A certification covers specific claims, not a whole standard. Look for these claims on the certifier’s listing, not the box. Wording varies a little: NSF writes “Lead Reduction,” WQA just “Lead.”

At the tap, or for the whole house?

Lead and copper usually come from pipes and fixtures inside or near your home. A whole-house system sits where water enters, so it cannot catch what your own plumbing adds after it. For those, the filter that counts is the one at the tap. How whole-house systems compare.

Filters with those claims on a certifier’s listing

Disclosure: TapBuff earns a commission if you buy through some links on this page. It does not change which standard or filter we name. As an Amazon Associate, TapBuff earns from qualifying purchases. How TapBuff makes money

Compare five-year costs

The best water filters for lead, ranked

Violations since 2016

Contaminant or ruleTypePeriodMeasuredStatus
Groundwater RuleRequired treatment for surface water or groundwater was not met.EPA: Treatment Technique (SWTR and GWR)June 1, 2025 to June 30, 2025—Resolved
Gross alpha radiation (excluding radon and uranium)The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJan. 1, 2021 to March 31, 202117 PCI/LResolved
Combined Radium (-226 and -228)The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJan. 1, 2021 to March 31, 20216.0 PCI/LResolved
Gross alpha radiation (excluding radon and uranium)The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageOct. 1, 2020 to Dec. 31, 202019 PCI/LResolved
Combined Radium (-226 and -228)The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageOct. 1, 2020 to Dec. 31, 20206.0 PCI/LResolved
Combined Radium (-226 and -228)The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJuly 1, 2020 to Sept. 30, 20206.0 PCI/LResolved
Gross alpha radiation (excluding radon and uranium)The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJuly 1, 2020 to Sept. 30, 202020 PCI/LResolved
Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record.

What this report can’t tell you

  • Everything else. Uranium, total trihalomethanes (TTHM), nitrate, haloacetic acids (HAA5) and arsenic results here are New York’s own yearly summaries from 2020 on, with EPA’s national file for 2012 to 2019. Chromium (total) and fluoride come from EPA’s file alone, which ends in 2019. Indian Hill Subdivision’s own annual report, which it must send you every year, has newer results for those and the contaminants this page does not show.

  • Your own plumbing. Lead results are the 90th percentile across homes the utility samples. Your home’s service line, solder and fixtures decide yours. A certified lab test is the only way to know.

  • What it means for your health. This page reports what the records show and EPA’s limits and goals; it is not medical advice. If you are worried about a health effect, talk to a doctor or your local health department.

  • Anything after the latest data. SDWIS data is from 2026 Q3; UCMR 5 didn’t sample this utility; New York’s yearly summaries cover 2020 to 2024; EPA’s compliance samples are from Aug. 6, 2013 to Sept. 18, 2018.

Testing your own tap

Indian Hill Subdivision’s results are for the water it sends out. What your own service line, solder and fixtures add shows up only in a test of your tap, by a lab New York certifies.

The 3 labs New York certifies closest to the area Indian Hill Subdivision serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

  • Yorktown Medical Laboratory Inc.

    Yorktown Heights, NY · about 6 miles

    Certified for bacteria, nitrate, lead and copper

    (914) 245-3203

  • Westchester Co Labs and Research

    Valhalla, NY · about 14 miles

    Certified for bacteria, nitrate, lead and copper, metals, minerals and other inorganics, organic chemicals, disinfection byproducts, PFAS

    (914) 231-1768

  • EAS Inc. - Eastern Analytical Services Inc.

    Elmsford, NY · about 16 miles

    Certified for lead and copper, asbestos

    (914) 592-8380

All 161 certified labs for New York

Sources

PWSID NY5918382. Rebuilt from EPA data on Oct. 18, 2026.

Also in Westchester County

All New York utilities

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