Seawood Estates Mutual Water Company
What EPA’s and California’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
- 63 people
- Connections
- 25
- Water source
- Surface water
- Based in
- Trinidad, CA
- County
- Humboldt
- Owner
- Private
The ZIP code it serves
The short answer
1 result is above the limit’s level with no violation recorded. The worst: Haloacetic acids (HAA5), above the limit’s level, no violation. No health-based violations on file since 2016.
What was found
Copper: EPA’s file records a utility’s copper only when it exceeds the action level. The last here was 1.6 ppm, for the period ending Dec. 31, 2008. None since is on file, so it is not counted as a current finding.
Haloacetic acids (HAA5), total trihalomethanes (TTHM) and nitrate: California’s own results, samples taken from March 22, 2020 to Feb. 3, 2026, with EPA’s 2012 to 2019 file for earlier years.
Arsenic, chromium (total) and fluoride: EPA’s compliance monitoring file, samples taken from Nov. 15, 2017 to Aug. 15, 2018. Newer results are in the utility’s annual water quality report.
Above the limit’s level, no violation recorded1
Haloacetic acids (HAA5)
Forms or is added in treatment
64.5ppb
Highest yearly average, 2020 to 2025
2025 average: 8.9 ppb
Averaged by year, the highest was 64.5 ppb, in 2022, above EPA’s legal limit of 60 ppb. Its highest single sample was 132 ppb. In 2025, the latest year on file, its three samples averaged 8.9 ppb. EPA judges this limit on running averages at each sampling point, and recorded no violation for haloacetic acids (HAA5) at this utility since 2020. Results like these with no violation often include water sampled before treatment or blending; the utility’s annual report says what reaches the tap. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 25.1 ppb, in 2019.
What handles it
No certification claim covers this compound yet.
Below EPA’s limits1
Total trihalomethanes (TTHM)
Forms or is added in treatment
66.8ppb
Highest yearly average, 2020 to 2025
2025 average: 21.9 ppb
Averaged by year, the highest was 66.8 ppb, in 2022, below EPA’s legal limit of 80 ppb. Its highest single sample was 130 ppb. In 2025, the latest year on file, its three samples averaged 21.9 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 39.3 ppb, in 2019.
What handles it
- NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
- NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”
5 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
- Arsenic
- Chromium (total)
- Fluoride
- Lead
- Nitrate
Violations since 2016
No health-based violations on file with EPA since 2016. There are 3 monitoring or reporting violations: a sample missed, late or not reported.
What this report can’t tell you
Everything else. Haloacetic acids (HAA5), total trihalomethanes (TTHM) and nitrate results here are California’s own from 2020 on, with EPA’s national file for 2012 to 2019. Arsenic, chromium (total) and fluoride come from EPA’s file alone, which ends in 2019. Seawood Estates Mutual Water Company’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; California’s results run from March 22, 2020 to Feb. 3, 2026; EPA’s compliance samples are from Nov. 15, 2017 to Aug. 15, 2018.
Testing your own tap
The 2 labs California certifies closest to the area Seawood Estates Mutual Water Company serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.
Microbac Laboratories, Inc. - Arcata
Arcata, CA · about 13 miles
Certified for bacteria, nitrate, lead and copper, metals, minerals and other inorganics, organic chemicals, disinfection byproducts
Humboldt County Public Health Laboratory
Eureka, CA · about 19 miles
Certified for bacteria
Sources
- EPA UCMR 5 occurrence data, file of Oct. 15, 2026
- EPA SDWA bulk download (SDWIS federal data), 2026 Q3
- California State Water Resources Control Board, Division of Drinking Water, results from Jan. 1, 2020 to July 17, 2026, read Oct. 8, 2026
- EPA Six-Year Review 4 compliance monitoring data, 2012 to 2019, file of Feb. 5, 2024
- Certified labs: California State Water Resources Control Board, ELAP accredited laboratories and their fields of accreditation, read Oct. 17, 2026; distances from the Census 2020 ZIP code tabulation area gazetteer
- Limits and goals: each contaminant’s page, with its EPA source.
- How this page is built: methodology.
PWSID CA1200588. Rebuilt from EPA data on Oct. 18, 2026.
What to do next
- Read up on Haloacetic acids (HAA5)What each one does to health, where it comes from, and the certification claim that addresses it.About Haloacetic acids (HAA5)
- Get the utility’s own reportSeawood Estates Mutual Water Company must send you a water quality report every year. It covers contaminants this page does not show, and has newer results than EPA’s national file for the ones here that come from it.How to read it
- Test your own tap for leadYour service line, solder and fixtures decide the lead at your faucet, not the utility’s average.Lead in your water: what to do
- Decide if you want a filter at allA filter for taste or chlorine is a preference, not a need. The standards say what each kind can do.NSF/ANSI standards, decoded