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Shirona Water System

What EPA’s and Washington’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
243 people
Connections
102
Water source
Groundwater
Based in
Coupeville, WA
County
Island
Owner
Private
Hardness
Very hard
The ZIP code it serves

98277

The short answer

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

What handles it

What was found

Lead and copper: EPA SDWIS monitoring periods ending 2007 to 2023.

Copper: EPA’s file records a utility’s copper only when it exceeds the action level. The last here was 1.7 ppm, for the period ending Dec. 31, 2010. None since is on file, so it is not counted as a current finding.

Total trihalomethanes (TTHM), haloacetic acids (HAA5), fluoride, arsenic, chromium (total) and nitrate: Washington’s own results, samples taken from Sept. 30, 2020 to Sept. 10, 2026, with EPA’s 2012 to 2019 file for earlier years.

Above the legal limit1

Total trihalomethanes (TTHM)

Forms or is added in treatment

Above the legal limit

86.7ppb

Highest yearly average, 2024 to 2026

2026 average: 79.5 ppb

Averaged by year, the highest was 86.7 ppb, in 2025, above EPA’s legal limit of 80 ppb. Its highest single sample was 137 ppb. In 2026, the latest year on file, its three samples averaged 79.5 ppb. EPA recorded violations for total trihalomethanes (TTHM) at this utility in 2025 and 2026. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 70.8 ppb, in 2014.

What handles it

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

Above the health goal1

Lead

Comes from pipes, often your own

Above the health goal

5.5ppb

90th percentile, 2021 to 2023

In the latest period, 9 in 10 homes sampled were at or below 5.5 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 limits2

Haloacetic acids (HAA5)

Forms or is added in treatment

Below EPA’s limits

25.1ppb

Highest yearly average, 2024 to 2026

Averaged by year, the highest was 25.1 ppb, in 2026, below EPA’s legal limit of 60 ppb. Its highest single sample was 41.8 ppb. That was also the latest year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 42.2 ppb, in 2012.

What handles it

No certification claim covers this compound yet.

Fluoride

Forms or is added in treatment

Below EPA’s limits

0.17ppm

Highest yearly average, 2024

Averaged by year, the highest was 0.17 ppm, in 2024, below EPA’s legal limit of 4.0 ppm. That is the only year on file.

What handles it

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

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

    For: Total trihalomethanes (TTHM), Lead

    Other certifiers’ wording: VOC Reduction

  • NSF/ANSI 58

    Claims: Trihalomethanes (TTHM) Reduction, Lead Reduction

    For: Total trihalomethanes (TTHM), 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

Hardness

Very hard, typically 300 mg/L (17.5 grains per gallon), across 3 sampling points, 2024 to 2026.

Hardness is calcium and magnesium. EPA sets no limit for it: it shows up as scale on fixtures and in water heaters, and as soap that won’t lather. USGS calls water above 60 mg/L moderately hard, above 120 hard and above 180 very hard.

Softeners compared at 17.5 grains per gallon, salt includedSoftener or salt-free conditioner?Washington water hardness, utility by utility

Violations since 2016

Contaminant or ruleTypePeriodMeasuredStatus
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageApril 1, 2026 to June 30, 202690.9 UG/LArchived
TTHMThe running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageOct. 1, 2025 to Dec. 31, 202590 UG/LArchived
Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. 6 monitoring or reporting violations not shown.

What this report can’t tell you

  • Everything else. Total trihalomethanes (TTHM), haloacetic acids (HAA5), fluoride, arsenic, chromium (total) and nitrate results here are Washington’s own from 2020 on, with EPA’s national file for 2012 to 2019. Shirona Water System’s own annual report, which it must send you every year, has 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; Washington’s results run from Sept. 30, 2020 to Sept. 10, 2026.

Testing your own tap

Shirona Water System’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 Washington certifies.

The 3 labs Washington certifies closest to the area Shirona Water System serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

  • Eurofins DW and WW West, Washington Laboratory

    Burlington, WA · about 18 miles

    Certified for bacteria, nitrate, minerals and other inorganics, disinfection byproducts

    (360) 757-1400

  • Precision Analytical Laboratories, LLC

    Everett, WA · about 29 miles

    Certified for lead and copper, metals, minerals and other inorganics

    (425) 740-4597

  • Everett Environmental Laboratory

    Everett, WA · about 31 miles

    Certified for bacteria, nitrate, lead and copper, metals, minerals and other inorganics

    (425) 257-8230

All 84 certified labs for Washington

Sources

PWSID WA5378373. Rebuilt from EPA data on Oct. 18, 2026.

Also in Island County

All Washington utilities

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