Tierra Bonita Mutual Water
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
- 75 people
- Connections
- 32
- Water source
- Groundwater
- Based in
- Lancaster, CA
- County
- Los Angeles
- Owner
- Private
- Hardness
- Moderately hard
The ZIP code it serves
The short answer
2 results are above the health goal. The worst: Nitrate, above the health goal. No health-based violations on file since 2016.
What handles itWhat was found
Nitrate, chromium (total), fluoride, arsenic and total trihalomethanes (TTHM): California’s own results, samples taken from Sept. 16, 2020 to April 15, 2026, with EPA’s 2012 to 2019 file for earlier years.
Uranium: EPA’s compliance monitoring file, samples taken from April 22, 2014 to March 14, 2016. Newer results are in the utility’s annual water quality report.
Above the health goal2
Nitrate
Comes from the source
11.2ppm
Highest sample; found in 9 of 9
2026, one sample: 2.4 ppm
One sample, in 2024, was above EPA’s legal limit of 10 ppm, at 11.2 ppm. No follow-up sample at that point within 30 days is on file. 10 ppm is also EPA’s health goal. In 2026, the latest year on file, its one sample was 2.4 ppm. EPA recorded no violation for nitrate at this utility since 2020. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 2.8 ppm, in 2018.
What handles it
- NSF/ANSI 58 look for “Nitrate/Nitrite Reduction”
- NSF/ANSI 53 look for “Nitrate/Nitrite (30 ppm challenge)”
Uranium
Comes from the source
1.2ppb
Highest yearly average, 2014 to 2016
2016, one sample: 0.77 ppb
Averaged by year, the highest was 1.2 ppb, in 2015: below EPA’s legal limit of 30 ppb, but above its health goal of zero. Its highest single sample was 1.9 ppb. In 2016, the latest year on file, its one sample was 0.77 ppb.
What handles it
- NSF/ANSI 58 look for “Uranium”
Below EPA’s limits2
Chromium (total)
Comes from the source
11ppb
Highest yearly average, 2021 to 2024
Averaged by year, the highest was 11 ppb, in 2024, below EPA’s legal limit of 100 ppb. That was also the latest year on file.
What handles it
- NSF/ANSI 58 look for “Chromium (Hexavalent) Reduction”
- NSF/ANSI 53 look for “Chromium Reduction”
Fluoride
Forms or is added in treatment
0.1ppm
Highest yearly average, 2021 to 2024
Averaged by year, the highest was 0.1 ppm, in 2024, below EPA’s legal limit of 4.0 ppm. That was also the latest year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.13 ppm, in 2015.
What handles it
- NSF/ANSI 58 look for “Fluoride Reduction”
- NSF/ANSI 53 look for “Fluoride”
3 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
- Arsenic
- Lead
- Total trihalomethanes (TTHM)
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: Nitrate/Nitrite (30 ppm challenge)
For: Nitrate
- NSF/ANSI 58
Claims: Nitrate/Nitrite Reduction, Uranium
For: Nitrate, Uranium
Other certifiers’ wording: Nitrate
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: Nitrate
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: Nitrate
Culligan 10-Cup Pitcher with ZeroWater Technology (ZEROP10)
Pitcher
- IAPMO listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 401checked Oct. 9, 2026
Certified for: Nitrate
Hardness
Moderately hard, 108 mg/L (6.3 grains per gallon), at its one sampling point, 2021 to 2024.
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 are 2 monitoring or reporting violations: a sample missed, late or not reported.
What this report can’t tell you
Everything else. Nitrate, chromium (total), fluoride, arsenic and total trihalomethanes (TTHM) results here are California’s own from 2020 on, with EPA’s national file for 2012 to 2019. Uranium comes from EPA’s file alone, which ends in 2019. Tierra Bonita Mutual Water’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 Sept. 16, 2020 to April 15, 2026; EPA’s compliance samples are from April 22, 2014 to March 14, 2016.
Testing your own tap
The 3 labs California certifies closest to the area Tierra Bonita Mutual Water serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.
Geo-Monitor, Inc
Hesperia, CA · about 37 miles
Certified for bacteria
Pat-Chem Laboratories
San Fernando, CA · about 44 miles
Certified for bacteria, nitrate, lead and copper, metals, minerals and other inorganics, organic chemicals, disinfection byproducts, radioactivity
EMSL Analytical, Inc. (LA Testing)
South Pasadena, CA · about 45 miles
Certified for bacteria, asbestos
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 Dec. 15, 2021 to May 15, 2024, read Oct. 10, 2026
- Limits and goals: each contaminant’s page, with its EPA source.
- How this page is built: methodology.
PWSID CA1900154. Rebuilt from EPA data on Oct. 18, 2026.
What to do next
- Read up on the 2 results above a lineWhat each one does to health, where it comes from, and the certification claim that addresses it.Start with Nitrate
- Get the utility’s own reportTierra Bonita Mutual Water 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
- Compare certified filtersWhat the filters certified for these results cost over five years, cartridges included.Compare five-year costs