Redwood Heights 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: 30 people
Connections: 18
Water source: Groundwater influenced by surface water
Based in: Cazadero, CA
County: Sonoma
Owner: Private
Hardness: Hard

The ZIP code it serves

95421

The short answer

Nothing in EPA’s and California’s records for this utility is above a health goal. That covers nitrate, arsenic and other regulated chemicals, plus lead and copper, not everything. No health-based violations on file since 2016.

What was found

Haloacetic acids (HAA5), total trihalomethanes (TTHM), nitrate, chromium (total), arsenic and fluoride: California’s own results, samples taken from July 21, 2020 to April 15, 2026, with EPA’s 2012 to 2019 file for earlier years.

Below EPA’s limits4

Haloacetic acids (HAA5)

Forms or is added in treatment

Below EPA’s limits

7.4ppb

Highest yearly average, 2020 to 2025

2025: not found

Averaged by year, the highest was 7.4 ppb, in 2022, below EPA’s legal limit of 60 ppb. Its highest single sample was 12.1 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 4.8 ppb, in 2016.

What handles it

No certification claim covers this compound yet.

Total trihalomethanes (TTHM)

Forms or is added in treatment

Below EPA’s limits

7.2ppb

Highest yearly average, 2020 to 2025

2025: not found

Averaged by year, the highest was 7.2 ppb, in 2022, below EPA’s legal limit of 80 ppb. Its highest single sample was 13.4 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 3.7 ppb, in 2018.

What handles it

NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”

Nitrate

Comes from the source

Below EPA’s limits

0.43ppm

Highest sample; found in 1 of 7

2026: not found

The highest sample, in 2023, was 0.43 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 0.17 ppm, in 2016.

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

1.6ppb

Highest yearly average, 2025

Averaged by year, the highest was 1.6 ppb, in 2025, below EPA’s legal limit of 100 ppb. That is the only year on file. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 2.6 ppb, in 2013.

What handles it

NSF/ANSI 58 look for “Chromium (Hexavalent) Reduction”
NSF/ANSI 53 look for “Chromium Reduction”

3 compounds tested and not foundBelow the reporting level in every sample. Not found is not the same as zero.

Arsenic
Fluoride
Lead

Hardness

Hard, 130 mg/L (7.6 grains per gallon), at its one sampling point, 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 7.6 grains per gallon, salt included Softener or salt-free conditioner?California water hardness, utility by utility

Violations since 2016

No health-based violations on file with EPA since 2016. There are 7 monitoring or reporting violations: a sample missed, late or not reported.

What this report can’t tell you

Everything else. Haloacetic acids (HAA5), total trihalomethanes (TTHM), nitrate, chromium (total), arsenic and fluoride results here are California’s own from 2020 on, with EPA’s national file for 2012 to 2019. Redwood Heights 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 July 21, 2020 to April 15, 2026.

Testing your own tap

Redwood Heights 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 Redwood Heights Mutual Water Company serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.

K Prime, LLC.
Santa Rosa, CA · about 21 miles
Certified for bacteria, nitrate, lead and copper, metals, minerals and other inorganics, PFAS
(707) 527-7574
Sonoma County Public Health Laboratory
Santa Rosa, CA · about 27 miles
Certified for bacteria
(707) 565-4711
Brelje and Race Laboratories, Inc.
Santa Rosa, CA · about 28 miles
Certified for bacteria, nitrate, lead and copper, metals, minerals and other inorganics, organic chemicals, disinfection byproducts
(707) 544-8807