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Thunderbird Terrace 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
75 people
Connections
30
Water source
Surface water
Based in
Monroe, WA
County
Snohomish
Owner
Private
Hardness
Soft
The ZIP code it serves

98272

The short answer

1 result is above EPA’s legal limit, and 1 more is above the health goal. The worst: Haloacetic acids (HAA5), above the legal limit. 1 health-based violation since 2016.

What handles it

What was found

Lead and copper: EPA SDWIS monitoring periods ending 2005 to 2025.

Haloacetic acids (HAA5), total trihalomethanes (TTHM) and nitrate: Washington’s own results, samples taken from March 15, 2020 to April 19, 2026, with EPA’s 2012 to 2019 file for earlier years.

Above the legal limit1

Haloacetic acids (HAA5)

Forms or is added in treatment

Above the legal limit

47.2ppb

Highest yearly average, 2020 to 2025

2025, one sample: 17.7 ppb

Averaged by year, the highest was 47.2 ppb, in 2020, below EPA’s legal limit of 60 ppb. Its highest single sample was 57 ppb. In 2025, the latest year on file, its one sample was 17.7 ppb. EPA judges this limit at each sampling point, and recorded a violation for haloacetic acids (HAA5) at this utility in 2020. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 86.9 ppb, in 2019.

What handles it

No certification claim covers this compound yet.

Above the health goal1

Lead

Comes from pipes, often your own

Above the health goal

0.6ppb

90th percentile, 2023 to 2025

In the latest period, 9 in 10 homes sampled were at or below 0.6 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

Total trihalomethanes (TTHM)

Forms or is added in treatment

Below EPA’s limits

42.9ppb

Highest yearly average, 2020 to 2025

2025, one sample: 42.4 ppb

Averaged by year, the highest was 42.9 ppb, in 2021, below EPA’s legal limit of 80 ppb. Its highest single sample was 53.5 ppb. In 2025, the latest year on file, its one sample was 42.4 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 45.9 ppb, in 2015.

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

0.75ppm

Highest sample; found in 5 of 6

2026, one sample: 0.75 ppm

The highest sample, in 2026, was 0.75 ppm, below EPA’s legal limit of 10 ppm. That was also the latest year on file, and its one sample was 0.75 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 1.1 ppm, in 2016.

What handles it

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

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

Hardness

Soft, 26 mg/L (1.5 grains per gallon), at its one sampling point, in 2020.

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 1.5 grains per gallon, salt includedSoftener or salt-free conditioner?Washington water hardness, utility by utility

Violations since 2016

Contaminant or ruleTypePeriodMeasuredStatus
Total Haloacetic Acids (HAA5)The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, AverageApril 1, 2020 to June 30, 202069.1 UG/LResolved
Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. 7 monitoring or reporting violations not shown.

What this report can’t tell you

  • Everything else. Haloacetic acids (HAA5), total trihalomethanes (TTHM) and nitrate results here are Washington’s own from 2020 on, with EPA’s national file for 2012 to 2019. Thunderbird Terrace 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 March 15, 2020 to April 19, 2026.

Testing your own tap

Thunderbird Terrace 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 Thunderbird Terrace Water System serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

  • Everett Environmental Laboratory

    Everett, WA · about 15 miles

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

    (425) 257-8230

  • OnSite Environmental, Inc.

    Redmond, WA · about 16 miles

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

    (425) 883-3881

  • Precision Analytical Laboratories, LLC

    Everett, WA · about 18 miles

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

    (425) 740-4597

All 84 certified labs for Washington

Sources

PWSID WA5305067. Rebuilt from EPA data on Oct. 18, 2026.

Towns it serves

Also in Snohomish County

All Washington utilities

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