Cws - Kernville
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
- 2,376 people
- Connections
- 1,878
- Water source
- Surface water
- Based in
- San Jose, CA
- County
- Kern
- Owner
- Private
- Hardness
- Varies by source
The ZIP code it serves
The short answer
3 results are above the health goal. The worst: Lead, above the health goal. 12 health-based violations since 2016.
What handles itWhat was found
Lead and copper: EPA SDWIS monitoring periods ending 2008 to 2025.
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, 2006. None since is on file, so it is not counted as a current finding.
Arsenic, uranium, haloacetic acids (HAA5), fluoride, total trihalomethanes (TTHM), nitrate and chromium (total): California’s own results, samples taken from Jan. 28, 2020 to July 7, 2026, with EPA’s 2012 to 2019 file for earlier years.
Above the health goal3
Lead
Comes from pipes, often your own
7.4ppb
90th percentile, 2023 to 2025
In the latest period, 9 in 10 homes sampled were at or below 7.4 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
- NSF/ANSI 53 look for “Lead Reduction”
- NSF/ANSI 58 look for “Lead Reduction”
Arsenic
Comes from the source
2.8ppb
Highest yearly average, 2020 to 2026
2026 average: 0.79 ppb
Averaged by year, the highest was 2.8 ppb, in 2022: below EPA’s legal limit of 10 ppb, but above its health goal of zero. Its highest single sample was 31 ppb. In 2026, the latest year on file, its nine samples averaged 0.79 ppb. EPA recorded no violation for arsenic at this utility since 2020. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 9.4 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”
Uranium
Comes from the source
2.2ppb
Highest yearly average, 2020 to 2026
2026: not found
Averaged by year, the highest was 2.2 ppb, in 2021: below EPA’s legal limit of 30 ppb, but above its health goal of zero. Its highest single sample was 4.8 ppb. In 2026, the latest year on file, it wasn’t found in any of its five samples. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 8.1 ppb, in 2012.
What handles it
- NSF/ANSI 58 look for “Uranium”
Below EPA’s limits5
Haloacetic acids (HAA5)
Forms or is added in treatment
19.8ppb
Highest yearly average, 2020 to 2026
2026 average: 16.5 ppb
Averaged by year, the highest was 19.8 ppb, in 2025, below EPA’s legal limit of 60 ppb. Its highest single sample was 67 ppb. In 2026, the latest year on file, its 39 samples averaged 16.5 ppb. EPA recorded no violation for haloacetic acids (HAA5) at this utility since 2020. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 75.5 ppb, in 2016, and EPA recorded violations in 2016, 2017, 2018 and 2019.
What handles it
No certification claim covers this compound yet.
Fluoride
Forms or is added in treatment
1.3ppm
Highest yearly average, 2020 to 2026
2026 average: 0.96 ppm
Averaged by year, the highest was 1.3 ppm, in 2023, below EPA’s legal limit of 4.0 ppm. Its highest single sample was 2.5 ppm. In 2026, the latest year on file, its 32 samples averaged 0.96 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 1.8 ppm, in 2015.
What handles it
- NSF/ANSI 58 look for “Fluoride Reduction”
- NSF/ANSI 53 look for “Fluoride”
Total trihalomethanes (TTHM)
Forms or is added in treatment
24.9ppb
Highest yearly average, 2020 to 2026
2026 average: 15.1 ppb
Averaged by year, the highest was 24.9 ppb, in 2022, below EPA’s legal limit of 80 ppb. Its highest single sample was 66 ppb. In 2026, the latest year on file, its 37 samples averaged 15.1 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 59.6 ppb, in 2016.
What handles it
- NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
- NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”
Nitrate
Comes from the source
0.7ppm
Highest sample; found in 44 of 165
2026 average: 0.096 ppm
The highest sample, in 2022, was 0.7 ppm, below EPA’s legal limit of 10 ppm. In 2026, the latest year on file, its 25 samples averaged 0.096 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 1.5 ppm, in 2013.
What handles it
- NSF/ANSI 58 look for “Nitrate/Nitrite Reduction”
- NSF/ANSI 53 look for “Nitrate/Nitrite (30 ppm challenge)”
Chromium (total)
Comes from the source
1.3ppb
Highest yearly average, 2020 to 2026
2026 average: 0.87 ppb
Averaged by year, the highest was 1.3 ppb, in 2024, below EPA’s legal limit of 100 ppb. Its highest single sample was 4.5 ppb. In 2026, the latest year on file, its six samples averaged 0.87 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 1.3 ppb, in 2015.
What handles it
- NSF/ANSI 58 look for “Chromium (Hexavalent) Reduction”
- NSF/ANSI 53 look for “Chromium Reduction”
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: Lead Reduction, Arsenic (Pentavalent)<=50 ppb Reduction
For: Lead, Arsenic
Other certifiers’ wording: Arsenic (III) (50 ppb influent level)
- NSF/ANSI 58
Claims: Lead Reduction, Arsenic (Pentavalent)<=50 ppb Reduction, Uranium
For: Lead, Arsenic, Uranium
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
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: Lead, 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: Lead, Arsenic
Countertop reverse osmosis
- IAPMO listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 58NSF/ANSI 401checked Oct. 4, 2026
Certified for: Lead, Arsenic
Brita Tahoe Pitcher with Elite Filter (OB60, OB06)
Pitcher
- WQA listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 401checked Oct. 13, 2026
- IAPMO listing:NSF/ANSI 53checked Oct. 13, 2026
Certified for: Lead
Hardness
Soft to very hard depending on the source, 38 to 223 mg/L (2.2 to 13.1 grains per gallon), across 8 sampling points, 2019 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.
Violations since 2016
| Contaminant or rule | Type | Period | Measured | Status |
|---|---|---|---|---|
| Total Haloacetic Acids (HAA5) | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Oct. 1, 2019 to Dec. 31, 2019 | 0.067 MG/L | Resolved |
| Total Haloacetic Acids (HAA5) | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | July 1, 2019 to Sept. 30, 2019 | 0.061 MG/L | Resolved |
| Total Haloacetic Acids (HAA5) | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | April 1, 2019 to June 30, 2019 | 0.063 MG/L | Resolved |
| Total Haloacetic Acids (HAA5) | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Jan. 1, 2018 to March 31, 2018 | 0.064 MG/L | Resolved |
| Total Haloacetic Acids (HAA5) | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Oct. 1, 2017 to Dec. 31, 2017 | 0.084 MG/L | Resolved |
| Total Haloacetic Acids (HAA5) | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | July 1, 2017 to Sept. 30, 2017 | 0.069 MG/L | Resolved |
| Total Haloacetic Acids (HAA5) | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | April 1, 2017 to June 30, 2017 | 0.064 MG/L | Resolved |
| Total Haloacetic Acids (HAA5) | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Jan. 1, 2017 to March 31, 2017 | 0.072 MG/L | Resolved |
| Total Haloacetic Acids (HAA5) | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Oct. 1, 2016 to Dec. 31, 2016 | 0.079 MG/L | Resolved |
| Total Haloacetic Acids (HAA5) | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | July 1, 2016 to Sept. 30, 2016 | 0.08 MG/L | Resolved |
| Total Haloacetic Acids (HAA5) | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | April 1, 2016 to June 30, 2016 | 0.087 MG/L | Resolved |
| Total Haloacetic Acids (HAA5) | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Jan. 1, 2016 to March 31, 2016 | 0.074 MG/L | Resolved |
| Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. | ||||
What this report can’t tell you
Everything else. Arsenic, uranium, haloacetic acids (HAA5), fluoride, total trihalomethanes (TTHM), nitrate and chromium (total) results here are California’s own from 2020 on, with EPA’s national file for 2012 to 2019. Cws - Kernville’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; California’s results run from Jan. 28, 2020 to July 7, 2026.
Testing your own tap
The 3 labs California certifies closest to the area Cws - Kernville serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.
Pace Analytical Services, LLC dba BC Laboratories, Inc.
Bakersfield, CA · about 43 miles
Certified for bacteria, nitrate, lead and copper, metals, minerals and other inorganics, organic chemicals, disinfection byproducts, radioactivity
Zalco Laboratories, Inc.
Bakersfield, CA · about 43 miles
Certified for bacteria, nitrate, metals, minerals and other inorganics, organic chemicals, disinfection byproducts
BSK Associates - Bakersfield Analytical Laboratory
Bakersfield, CA · about 48 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
- Hardness: California State Water Resources Control Board, Division of Drinking Water, results from Feb. 20, 2019 to April 20, 2026, read Oct. 10, 2026
- Limits and goals: each contaminant’s page, with its EPA source.
- How this page is built: methodology.
PWSID CA1510033. Rebuilt from EPA data on Oct. 18, 2026.
What to do next
- Read up on the 3 results above a lineWhat each one does to health, where it comes from, and the certification claim that addresses it.Start with Lead
- Get the utility’s own reportCws - Kernville 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