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Colorado 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
37 people
Connections
1
Water source
Groundwater
Based in
Lancaster, CA
County
Los Angeles
Owner
Private
Hardness
Very hard
The ZIP code it serves

93535

The short answer

1 result is above the health goal. The worst: Uranium, above the health goal. 1 health-based violation since 2016.

What handles it

What was found

Uranium, nitrate, fluoride, arsenic, chromium (total) and total trihalomethanes (TTHM): California’s own results, samples taken from Sept. 22, 2020 to Oct. 21, 2025, with EPA’s 2012 to 2019 file for earlier years.

Above the health goal1

Uranium

Comes from the source

Above the health goal

4.8ppb

Highest yearly average, 2024 to 2025

Averaged by year, the highest was 4.8 ppb, in 2025: below EPA’s legal limit of 30 ppb, but above its health goal of zero. That was also the latest year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 6.0 ppb, in 2017.

What handles it

Below EPA’s limits2

Nitrate

Comes from the source

Below EPA’s limits

3.0ppm

Highest sample; found in 10 of 11

2025, one sample: 2.4 ppm

The highest sample, in 2021, was 3.0 ppm, below EPA’s legal limit of 10 ppm. In 2025, the latest year on file, its one sample was 2.4 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 2.5 ppm, in 2018.

What handles it

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

Fluoride

Forms or is added in treatment

Below EPA’s limits

0.21ppm

Highest yearly average, 2021 to 2025

Averaged by year, the highest was 0.21 ppm, in 2025, 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 0.23 ppm, in 2016.

What handles it

4 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
  • Arsenic
  • Chromium (total)
  • 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.”

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

None of the filters TapBuff has checked so far carry these claims. Search the certifier listings for the claim above.

Compare five-year costs

Hardness

Very hard, typically 435 mg/L (25.4 grains per gallon), across 2 sampling points, 2019 to 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.

Softeners compared at 25.4 grains per gallon, salt includedSoftener or salt-free conditioner?California water hardness, utility by utility

Violations since 2016

Contaminant or ruleTypePeriodMeasuredStatus
Lead and Copper Rule RevisionsThe required inventory of lead service lines was not completed or submitted on time.EPA: LSL InventoryOct. 17, 2024—Unaddressed
Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. 1 monitoring or reporting violation not shown.

What this report can’t tell you

  • Everything else. Uranium, nitrate, fluoride, arsenic, chromium (total) and total trihalomethanes (TTHM) results here are California’s own from 2020 on, with EPA’s national file for 2012 to 2019. Colorado Mutual Water Company’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 Sept. 22, 2020 to Oct. 21, 2025.

Testing your own tap

Colorado Mutual Water Company’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 California certifies.

The 3 labs California certifies closest to the area Colorado Mutual Water Company 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

    (760) 244-3481

  • 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

    (800) 400-5227

  • EMSL Analytical, Inc. (LA Testing)

    South Pasadena, CA · about 45 miles

    Certified for bacteria, asbestos

    (323) 254-9960

All 145 certified labs for California

Sources

PWSID CA1900801. Rebuilt from EPA data on Oct. 18, 2026.

Also in Los Angeles County

All California utilities

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