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Las Cumbres Mutual Water Co

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
402 people
Connections
125
Water source
Surface water
Based in
Los Gatos, CA
County
Santa Cruz
Owner
Private
Hardness
Varies by source
The ZIP code it serves

95033

The short answer

2 results are above the health goal. The worst: Lead, above the health goal. 22 health-based violations since 2016.

What handles it

What was found

Lead and copper: EPA SDWIS monitoring periods ending 2012 to 2024.

Arsenic, total trihalomethanes (TTHM), haloacetic acids (HAA5), fluoride, nitrate, chromium (total) and uranium: California’s own results, samples taken from Jan. 7, 2020 to June 15, 2026, with EPA’s 2012 to 2019 file for earlier years.

Above the health goal2

Lead

Comes from pipes, often your own

Above the health goal

2.5ppb

90th percentile, 2022 to 2024

In the latest period, 9 in 10 homes sampled were at or below 2.5 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

Arsenic

Comes from the source

Above the health goal

0.22ppb

Highest yearly average, 2020 to 2026

2026: not found

Averaged by year, the highest was 0.22 ppb, in 2024: below EPA’s legal limit of 10 ppb, but above its health goal of zero. Its highest single sample was 1.3 ppb. In 2026, the latest year on file, it wasn’t found in its one sample. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.5 ppb, in 2015.

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 limits5

Total trihalomethanes (TTHM)

Forms or is added in treatment

Below EPA’s limits

43ppb

Highest yearly average, 2020 to 2025

Averaged by year, the highest was 43 ppb, in 2025, below EPA’s legal limit of 80 ppb. That was also the latest year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 22 ppb, in 2019.

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

Below EPA’s limits

27.5ppb

Highest yearly average, 2020 to 2025

2025: not found

Averaged by year, the highest was 27.5 ppb, in 2021, below EPA’s legal limit of 60 ppb. Its highest single sample was 29 ppb. In 2025, the latest year on file, it wasn’t found in its one sample. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 12 ppb, in 2017.

What handles it

No certification claim covers this compound yet.

Fluoride

Forms or is added in treatment

Below EPA’s limits

1.4ppm

Highest yearly average, 2020 to 2026

2026 average: 1.0 ppm

Averaged by year, the highest was 1.4 ppm, in 2021, below EPA’s legal limit of 4.0 ppm. Its highest single sample was 3.6 ppm. In 2026, the latest year on file, its 12 samples averaged 1.0 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 1.7 ppm, in 2018.

What handles it

Nitrate

Comes from the source

Below EPA’s limits

1.6ppm

Highest sample; found in 14 of 50

2026: not found

The highest sample, in 2022, was 1.6 ppm, below EPA’s legal limit of 10 ppm. In 2026, the latest year on file, it wasn’t found in its one sample. Earlier, from 2012 to 2019, EPA’s file shows a highest sample of 1.5 ppm, in 2015.

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

Below EPA’s limits

1.3ppb

Highest yearly average, 2020 to 2026

2026: not found

Averaged by year, the highest was 1.3 ppb, in 2021, below EPA’s legal limit of 100 ppb. Its highest single sample was 7.8 ppb. In 2026, the latest year on file, it wasn’t found in its one sample. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 2.5 ppb, in 2018.

What handles it

One compound tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.
  • Uranium

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

    For: Lead, Arsenic

    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

Compare five-year costs

The best water filters for lead, ranked

The best reverse osmosis systems, ranked

Hardness

Soft to very hard depending on the source, 9 to 228 mg/L (0.5 to 13.3 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.

Softeners compared, salt includedSoftener or salt-free conditioner?California water hardness, utility by utility

Violations since 2016

Contaminant or ruleTypePeriodMeasuredStatus
Surface Water Treatment RuleRequired treatment for surface water or groundwater was not met.EPA: Treatment Technique (SWTR and GWR)Nov. 1, 2016 to Nov. 30, 2016—Resolved
Surface Water Treatment RuleWater drawn from a river, lake or reservoir was not filtered as required.EPA: Failure to Filter (SWTR)Nov. 1, 2016—Resolved
Surface Water Treatment RuleRequired treatment for surface water or groundwater was not met.EPA: Treatment Technique (SWTR and GWR)Oct. 1, 2016 to Oct. 31, 2016—Resolved
Surface Water Treatment RuleWater drawn from a river, lake or reservoir was not filtered as required.EPA: Failure to Filter (SWTR)Oct. 1, 2016—Resolved
Surface Water Treatment RuleWater drawn from a river, lake or reservoir was not filtered as required.EPA: Failure to Filter (SWTR)Sept. 1, 2016—Resolved
Surface Water Treatment RuleRequired treatment for surface water or groundwater was not met.EPA: Treatment Technique (SWTR and GWR)Sept. 1, 2016 to Sept. 30, 2016—Resolved
Surface Water Treatment RuleWater drawn from a river, lake or reservoir was not filtered as required.EPA: Failure to Filter (SWTR)Aug. 1, 2016—Resolved
Surface Water Treatment RuleRequired treatment for surface water or groundwater was not met.EPA: Treatment Technique (SWTR and GWR)Aug. 1, 2016 to Aug. 31, 2016—Resolved
Surface Water Treatment RuleWater drawn from a river, lake or reservoir was not filtered as required.EPA: Failure to Filter (SWTR)July 1, 2016—Resolved
Surface Water Treatment RuleRequired treatment for surface water or groundwater was not met.EPA: Treatment Technique (SWTR and GWR)July 1, 2016 to July 31, 2016—Resolved
Surface Water Treatment RuleWater drawn from a river, lake or reservoir was not filtered as required.EPA: Failure to Filter (SWTR)June 1, 2016—Resolved
Surface Water Treatment RuleRequired treatment for surface water or groundwater was not met.EPA: Treatment Technique (SWTR and GWR)June 1, 2016 to June 30, 2016—Resolved
Surface Water Treatment RuleRequired treatment for surface water or groundwater was not met.EPA: Treatment Technique (SWTR and GWR)May 1, 2016 to May 31, 2016—Resolved
Surface Water Treatment RuleWater drawn from a river, lake or reservoir was not filtered as required.EPA: Failure to Filter (SWTR)May 1, 2016—Resolved
Surface Water Treatment RuleWater drawn from a river, lake or reservoir was not filtered as required.EPA: Failure to Filter (SWTR)April 1, 2016—Resolved
Surface Water Treatment RuleRequired treatment for surface water or groundwater was not met.EPA: Treatment Technique (SWTR and GWR)April 1, 2016 to April 30, 2016—Resolved
Surface Water Treatment RuleRequired treatment for surface water or groundwater was not met.EPA: Treatment Technique (SWTR and GWR)March 1, 2016 to March 31, 2016—Resolved
Surface Water Treatment RuleWater drawn from a river, lake or reservoir was not filtered as required.EPA: Failure to Filter (SWTR)March 1, 2016—Resolved
Surface Water Treatment RuleWater drawn from a river, lake or reservoir was not filtered as required.EPA: Failure to Filter (SWTR)Feb. 1, 2016—Resolved
Surface Water Treatment RuleRequired treatment for surface water or groundwater was not met.EPA: Treatment Technique (SWTR and GWR)Feb. 1, 2016 to Feb. 29, 2016—Resolved
Surface Water Treatment RuleWater drawn from a river, lake or reservoir was not filtered as required.EPA: Failure to Filter (SWTR)Jan. 1, 2016—Resolved
Surface Water Treatment RuleRequired treatment for surface water or groundwater was not met.EPA: Treatment Technique (SWTR and GWR)Jan. 1, 2016 to Jan. 31, 2016—Resolved
Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. 5 monitoring or reporting violations not shown.

What this report can’t tell you

  • Everything else. Arsenic, total trihalomethanes (TTHM), haloacetic acids (HAA5), fluoride, nitrate, chromium (total) and uranium results here are California’s own from 2020 on, with EPA’s national file for 2012 to 2019. Las Cumbres Mutual Water Co’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. 7, 2020 to June 15, 2026.

Testing your own tap

Las Cumbres Mutual Water Co’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 Las Cumbres Mutual Water Co serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

  • Santa Cruz County - Health Services Agency - Environmental Health

    Santa Cruz, CA · about 12 miles

    Certified for bacteria

    (831) 454-4624

  • Torrent Laboratory, Inc

    Milpitas, CA · about 18 miles

    Certified for bacteria, nitrate, lead and copper, metals, minerals and other inorganics, organic chemicals, disinfection byproducts, PFAS

    (408) 263-5258

  • Bracewell Engineering, Inc.

    Morgan Hill, CA · about 19 miles

    Certified for bacteria, nitrate, minerals and other inorganics

    (669) 258-5821

All 145 certified labs for California

Sources

PWSID CA4400631. Rebuilt from EPA data on Oct. 18, 2026.

Also in Santa Cruz County

All California utilities

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