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Southwest Harbor Water & Sewer District

What EPA’s and CDC’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
2,480 people
Connections
992
Water source
Surface water
Based in
Southwest Hbr, ME
County
Hancock
Owner
Local government
The ZIP code it serves

04679

The short answer

1 result is above EPA’s legal limit, and 2 more are above the health goal. The worst: Total trihalomethanes (TTHM), above the legal limit. 7 health-based violations since 2016.

What handles it

What was found

Lead and copper: EPA SDWIS monitoring periods ending 2013 to 2024.

Total trihalomethanes (TTHM), arsenic, haloacetic acids (HAA5) and nitrate: Maine’s yearly averages per water system, as CDC’s Environmental Public Health Tracking Network publishes them, 2020 to 2023, with EPA’s 2012 to 2019 file for earlier years.

Fluoride, chromium (total) and uranium: EPA’s compliance monitoring file, samples taken from Jan. 19, 2012 to Dec. 18, 2019. Newer results are in the utility’s annual water quality report.

Above the legal limit1

Total trihalomethanes (TTHM)

Forms or is added in treatment

Above the legal limit

84ppb

Highest yearly average, 2020 to 2023

2023 average: 41.5 ppb

Averaged by year, the highest was 84 ppb, in 2020, above EPA’s legal limit of 80 ppb. In 2023, the latest year on file, it averaged 41.5 ppb. EPA recorded a violation for total trihalomethanes (TTHM) at this utility in 2020. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 88.8 ppb, in 2018, and EPA recorded violations in 2018 and 2019.

What handles it

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

Above the health goal2

Lead

Comes from pipes, often your own

Above the health goal

2.1ppb

90th percentile, 2022 to 2024

In the latest period, 9 in 10 homes sampled were at or below 2.1 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

Arsenic

Comes from the source

Above the health goal

1.0ppb

Highest yearly average, 2020 to 2023

2023: not found

Averaged by year, the highest was 1.0 ppb, in 2021: below EPA’s legal limit of 10 ppb, but above its health goal of zero. In 2023, the latest year on file, it wasn’t found.

What handles it

  • NSF/ANSI 58 look for “Arsenic (Pentavalent)<=50 ppb Reduction”
  • NSF/ANSI 53 look for “Arsenic (Pentavalent)<=50 ppb Reduction”

Below EPA’s limits2

Haloacetic acids (HAA5)

Forms or is added in treatment

Below EPA’s limits

50.8ppb

Highest yearly average, 2020 to 2023

2023 average: 35.3 ppb

Averaged by year, the highest was 50.8 ppb, in 2020, below EPA’s legal limit of 60 ppb. In 2023, the latest year on file, it averaged 35.3 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 59.8 ppb, in 2019.

What handles it

No certification claim covers this compound yet.

Fluoride

Forms or is added in treatment

Below EPA’s limits

0.78ppm

Highest yearly average, 2012 to 2019

2019: not found

Averaged by year, the highest was 0.78 ppm, in 2012, below EPA’s legal limit of 4.0 ppm. Its highest single sample was 1.1 ppm. In 2019, the latest year on file, it wasn’t found in its one sample.

What handles it

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

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.”

  • NSF/ANSI 53

    Claims: Trihalomethanes (TTHM) Reduction, Lead Reduction, Arsenic (Pentavalent)<=50 ppb Reduction

    For: Total trihalomethanes (TTHM), Lead, Arsenic

    Other certifiers’ wording: VOC Reduction; Arsenic (III) (50 ppb influent level)

  • NSF/ANSI 58

    Claims: Trihalomethanes (TTHM) Reduction, Lead Reduction, Arsenic (Pentavalent)<=50 ppb Reduction

    For: Total trihalomethanes (TTHM), Lead, Arsenic

    Other certifiers’ wording: Arsenic (Pentavalent)<=300 ppb Reduction; Arsenic (V) (300 ppb influent level)

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

The best reverse osmosis systems, ranked

Violations since 2016

Contaminant or ruleTypePeriodMeasuredStatus
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageApril 1, 2020 to June 30, 20200.097 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJan. 1, 2020 to March 31, 20200.092 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageOct. 1, 2019 to Dec. 31, 20190.11 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJuly 1, 2019 to Sept. 30, 20190.16 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageJan. 1, 2019 to March 31, 20190.091 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageOct. 1, 2018 to Dec. 31, 201824 MG/LResolved
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageApril 1, 2018 to June 30, 201829.8 MG/LResolved
Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. 24 monitoring or reporting violations not shown.

What this report can’t tell you

  • Everything else. Total trihalomethanes (TTHM), arsenic, haloacetic acids (HAA5) and nitrate results here are Maine’s yearly averages as CDC publishes them, from 2020 on, with EPA’s national file for 2012 to 2019. Fluoride, chromium (total) and uranium come from EPA’s file alone, which ends in 2019. Southwest Harbor Water & Sewer District’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; CDC’s yearly averages for Maine cover 2020 to 2023; EPA’s compliance samples are from Jan. 19, 2012 to Dec. 18, 2019.

Testing your own tap

Southwest Harbor Water & Sewer District’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 Maine certifies.

The 3 labs Maine certifies closest to the area Southwest Harbor Water & Sewer District serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

Maine Health and Environmental Testing Laboratory: Well water test kits ordered online, from a bacteria-only test to full panels for new wells and home sales. The lab must receive the sample within 30 hours of collection. The basic safety test is $42, bacteria alone $27, first-draw lead $32, and the fuller well tests $127 to $147. Maine Private Well and Radiological Water and Air Test.

All 53 certified labs for Maine

Sources

PWSID ME0091490. Rebuilt from EPA data on Oct. 18, 2026.

Also in Hancock County

All Maine utilities

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