Bayshore 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
- 56 people
- Connections
- 36
- Water source
- Groundwater
- Based in
- MT Vernon, WA
- County
- Island
- Owner
- Private
- Hardness
- Hard
The ZIP code it serves
The short answer
1 result is above the health goal. The worst: Arsenic, above the health goal. No health-based violations on file since 2016.
What handles itWhat was found
Arsenic, total trihalomethanes (TTHM), haloacetic acids (HAA5), fluoride, chromium (total) and nitrate: Washington’s own results, samples taken from Aug. 27, 2020 to Aug. 19, 2026, with EPA’s 2012 to 2019 file for earlier years.
Above the health goal1
Arsenic
Comes from the source
4.8ppb
Highest yearly average, 2025
Averaged by year, the highest was 4.8 ppb, in 2025: below EPA’s legal limit of 10 ppb, but above its health goal of zero. That is the only year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 3.2 ppb, in 2016.
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 limits4
Total trihalomethanes (TTHM)
Forms or is added in treatment
62.6ppb
Highest yearly average, 2021 to 2026
2026, one sample: 42.1 ppb
Averaged by year, the highest was 62.6 ppb, in 2021, below EPA’s legal limit of 80 ppb. In 2026, the latest year on file, its one sample was 42.1 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 19.2 ppb, in 2018.
What handles it
- NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
- NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”
Haloacetic acids (HAA5)
Forms or is added in treatment
23.6ppb
Highest yearly average, 2021 to 2026
2026, one sample: 13 ppb
Averaged by year, the highest was 23.6 ppb, in 2023, below EPA’s legal limit of 60 ppb. In 2026, the latest year on file, its one sample was 13 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 4.7 ppb, in 2018.
What handles it
No certification claim covers this compound yet.
Fluoride
Forms or is added in treatment
0.18ppm
Highest yearly average, 2025
Averaged by year, the highest was 0.18 ppm, in 2025, below EPA’s legal limit of 4.0 ppm. That is the only year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.2 ppm, in 2016.
What handles it
- NSF/ANSI 58 look for “Fluoride Reduction”
- NSF/ANSI 53 look for “Fluoride”
Chromium (total)
Comes from the source
2.4ppb
Highest yearly average, 2025
Averaged by year, the highest was 2.4 ppb, in 2025, below EPA’s legal limit of 100 ppb. That is the only year on file.
What handles it
- NSF/ANSI 58 look for “Chromium (Hexavalent) Reduction”
- NSF/ANSI 53 look for “Chromium Reduction”
2 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
- Lead
- 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
Claim: Arsenic (Pentavalent)<=50 ppb Reduction
For: Arsenic
Other certifiers’ wording: Arsenic (III) (50 ppb influent level)
- NSF/ANSI 58
Claim: Arsenic (Pentavalent)<=50 ppb Reduction
For: Arsenic
Other certifiers’ wording: Arsenic (Pentavalent)<=300 ppb Reduction; Arsenic (V) (300 ppb influent level)
At the tap, or for the whole house?
These come with the water itself, so a whole-house system certified for the same claims treats every tap and shower. A filter at the tap treats drinking water for much less. 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
Countertop reverse osmosis
- IAPMO listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 58NSF/ANSI 401checked Oct. 4, 2026
Certified for: Arsenic
Aquasana SmartFlow Reverse Osmosis (AQ-SFRO2)
Under-sink reverse osmosis
- WQA listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 58NSF/ANSI 401checked Oct. 9, 2026
Certified for: Arsenic
Brondell Capella RC250 Reverse Osmosis System
Under-sink reverse osmosis
- WQA listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 58NSF/ANSI 401checked Oct. 9, 2026
Certified for: Arsenic
Hardness
Hard, 140 mg/L (8.2 grains per gallon), at its one sampling point, in 2025.
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.
Violations since 2016
No health-based violations on file with EPA since 2016. There is 1 monitoring or reporting violation: a sample missed, late or not reported.
What this report can’t tell you
Everything else. Arsenic, total trihalomethanes (TTHM), haloacetic acids (HAA5), fluoride, chromium (total) and nitrate results here are Washington’s own from 2020 on, with EPA’s national file for 2012 to 2019. Bayshore 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 Aug. 27, 2020 to Aug. 19, 2026.
Testing your own tap
The 3 labs Washington certifies closest to the area Bayshore Water System serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.
Precision Analytical Laboratories, LLC
Everett, WA · about 20 miles
Certified for lead and copper, metals, minerals and other inorganics
Eurofins DW and WW West, Washington Laboratory
Burlington, WA · about 21 miles
Certified for bacteria, nitrate, minerals and other inorganics, disinfection byproducts
Everett Environmental Laboratory
Everett, WA · about 22 miles
Certified for bacteria, nitrate, lead and copper, metals, minerals and other inorganics
Sources
- EPA UCMR 5 occurrence data, file of Oct. 15, 2026
- EPA SDWA bulk download (SDWIS federal data), 2026 Q3
- Washington State Department of Health, Office of Drinking Water, results from Jan. 1, 2020 to Sept. 29, 2026, read Oct. 8, 2026
- EPA Six-Year Review 4 compliance monitoring data, 2012 to 2019, file of Feb. 5, 2024
- Certified labs: Washington State Department of Ecology, Lab Accreditation Program, environmental laboratories accredited for drinking water analyses, read Oct. 10, 2026; distances from the Census 2020 ZIP code tabulation area gazetteer
- Hardness: Washington State Department of Health, Office of Drinking Water, results from Aug. 13, 2025 to Aug. 13, 2025, read Oct. 10, 2026
- Limits and goals: each contaminant’s page, with its EPA source.
- How this page is built: methodology.
PWSID WA5304930. Rebuilt from EPA data on Oct. 18, 2026.
What to do next
- Read up on ArsenicWhat each one does to health, where it comes from, and the certification claim that addresses it.About Arsenic
- Get the utility’s own reportBayshore Water System must send you a water quality report every year. It covers contaminants this page does not show.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
- Compare certified filtersWhat the filters certified for these results cost over five years, cartridges included.Compare five-year costs