Golden State Water Company - South Shore
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
- 24
- Water source
- Surface water
- Based in
- Rancho Cordova, CA
- County
- Lake
- Owner
- Private
- Hardness
- Hard
The ZIP code it serves
The short answer
2 results are above EPA’s legal limit, and 2 more are above the health goal. The worst: Haloacetic acids (HAA5), above the legal limit. 23 health-based violations since 2016.
What handles itWhat was found
Lead and copper: EPA SDWIS monitoring periods ending 2001 to 2024.
Haloacetic acids (HAA5), total trihalomethanes (TTHM), arsenic, nitrate, fluoride, chromium (total) and uranium: California’s own results, samples taken from Feb. 20, 2020 to June 25, 2026, with EPA’s 2012 to 2019 file for earlier years.
Above the legal limit2
Haloacetic acids (HAA5)
Forms or is added in treatment
99.3ppb
Highest yearly average, 2020 to 2026
2026 average: 72.5 ppb
Averaged by year, the highest was 99.3 ppb, in 2022, above EPA’s legal limit of 60 ppb. Its highest single sample was 152 ppb. In 2026, the latest year on file, its two samples averaged 72.5 ppb, above the limit. EPA recorded violations for haloacetic acids (HAA5) at this utility in 2020, 2021 and 2023. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 146 ppb, in 2018, and EPA recorded violations in 2016, 2017, 2018 and 2019.
What handles it
No certification claim covers this compound yet.
Total trihalomethanes (TTHM)
Forms or is added in treatment
122ppb
Highest yearly average, 2020 to 2026
2026 average: 95 ppb
Averaged by year, the highest was 122 ppb, in 2024, above EPA’s legal limit of 80 ppb. Its highest single sample was 260 ppb. In 2026, the latest year on file, its two samples averaged 95 ppb, above the limit. EPA recorded a violation for total trihalomethanes (TTHM) at this utility in 2023. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 105 ppb, in 2012, and EPA recorded violations in 2013 and 2016.
What handles it
- NSF/ANSI 53 look for “Trihalomethanes (TTHM) Reduction”
- NSF/ANSI 58 look for “Trihalomethanes (TTHM) Reduction”
Above the health goal2
Arsenic
Comes from the source
3.1ppb
Highest yearly average, 2020 to 2026
2026, one sample: 1.4 ppb
Averaged by year, the highest was 3.1 ppb, in 2023: below EPA’s legal limit of 10 ppb, but above its health goal of zero. In 2026, the latest year on file, its one sample was 1.4 ppb. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 2.0 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”
Lead
Comes from pipes, often your own
2.8ppb
90th percentile, 2022 to 2024
In the latest period, 9 in 10 homes sampled were at or below 2.8 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”
Below EPA’s limits3
Nitrate
Comes from the source
0.69ppm
Highest sample; found in 2 of 7
2026: not found
The highest sample, in 2020, was 0.69 ppm, below EPA’s legal limit of 10 ppm. In 2026, the latest year on file, it wasn’t found in its one sample.
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
0.26ppm
Highest yearly average, 2020 to 2026
2026, one sample: 0.13 ppm
Averaged by year, the highest was 0.26 ppm, in 2020, below EPA’s legal limit of 4.0 ppm. In 2026, the latest year on file, its one sample was 0.13 ppm. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 0.22 ppm, in 2015.
What handles it
- NSF/ANSI 58 look for “Fluoride Reduction”
- NSF/ANSI 53 look for “Fluoride”
Chromium (total)
Comes from the source
1.6ppb
Highest yearly average, 2020 to 2026
2026: not found
Averaged by year, the highest was 1.6 ppb, in 2020, below EPA’s legal limit of 100 ppb. In 2026, the latest year on file, it wasn’t found in its one sample.
What handles it
- NSF/ANSI 58 look for “Chromium (Hexavalent) Reduction”
- NSF/ANSI 53 look for “Chromium Reduction”
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: Trihalomethanes (TTHM) Reduction, Arsenic (Pentavalent)<=50 ppb Reduction, Lead Reduction
For: Total trihalomethanes (TTHM), Arsenic, Lead
Other certifiers’ wording: VOC Reduction; Arsenic (III) (50 ppb influent level)
- NSF/ANSI 58
Claims: Trihalomethanes (TTHM) Reduction, Arsenic (Pentavalent)<=50 ppb Reduction, Lead Reduction
For: Total trihalomethanes (TTHM), Arsenic, Lead
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: Total trihalomethanes (TTHM), Arsenic, Lead
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: Total trihalomethanes (TTHM), Arsenic, Lead
Countertop reverse osmosis
- IAPMO listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 58NSF/ANSI 401checked Oct. 4, 2026
Certified for: Total trihalomethanes (TTHM), Arsenic, Lead
Aquasana Clean Water Machine (AQ-CWM2)
Countertop
- WQA listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 401checked Oct. 9, 2026
Certified for: Total trihalomethanes (TTHM), Lead
Brita Hub Countertop Water Filter System (87340)
Countertop
- WQA listing:NSF/ANSI 42NSF/ANSI 53NSF/ANSI 401checked Oct. 9, 2026
- IAPMO listing:NSF/ANSI 53checked Oct. 9, 2026
Certified for: Total trihalomethanes (TTHM), Lead
Hardness
Hard, 155 mg/L (9.1 grains per gallon), at its one sampling point, 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 | July 1, 2023 to Sept. 30, 2023 | 87.2 UG/L | Archived |
| TTHM | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | April 1, 2023 to June 30, 2023 | 112 UG/L | Archived |
| Total Haloacetic Acids (HAA5) | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | April 1, 2023 to June 30, 2023 | 112 UG/L | Archived |
| Total Haloacetic Acids (HAA5) | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Jan. 1, 2023 to March 31, 2023 | 110 UG/L | Archived |
| Total Haloacetic Acids (HAA5) | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | April 1, 2021 to June 30, 2021 | 0.082 MG/L | Archived |
| Total Haloacetic Acids (HAA5) | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Jan. 1, 2021 to March 31, 2021 | 0.086 MG/L | Archived |
| Total Haloacetic Acids (HAA5) | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Oct. 1, 2020 to Dec. 31, 2020 | 0.078 MG/L | Archived |
| Total Haloacetic Acids (HAA5) | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | April 1, 2020 to June 30, 2020 | 0.079 MG/L | Archived |
| Total Haloacetic Acids (HAA5) | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Jan. 1, 2020 to March 31, 2020 | 0.079 MG/L | Archived |
| 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 | 0.085 MG/L | Archived |
| 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 | 0.093 MG/L | Archived |
| 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 | 0.1 MG/L | Archived |
| Total Haloacetic Acids (HAA5) | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Jan. 1, 2019 to March 31, 2019 | 124 UG/L | Archived |
| Total Haloacetic Acids (HAA5) | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Oct. 1, 2018 to Dec. 31, 2018 | 137 UG/L | Archived |
| Total Haloacetic Acids (HAA5) | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | July 1, 2018 to Sept. 30, 2018 | 148 UG/L | Archived |
| Total Haloacetic Acids (HAA5) | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | April 1, 2018 to June 30, 2018 | 140 UG/L | Archived |
| 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 | 101 UG/L | Archived |
| 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 | 83.2 UG/L | Archived |
| 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 | 65.9 UG/L | Archived |
| TTHM | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Oct. 1, 2016 to Dec. 31, 2016 | 0.097 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 | 0.076 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 | 71 UG/L | Resolved |
| TTHM | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | April 1, 2016 to June 30, 2016 | 108 UG/L | Resolved |
| 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. Haloacetic acids (HAA5), total trihalomethanes (TTHM), arsenic, nitrate, fluoride, chromium (total) and uranium results here are California’s own from 2020 on, with EPA’s national file for 2012 to 2019. Golden State Water Company - South Shore’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 Feb. 20, 2020 to June 25, 2026.
Testing your own tap
The 3 labs California certifies closest to the area Golden State Water Company - South Shore 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 30 miles
Certified for bacteria, nitrate, lead and copper, metals, minerals and other inorganics, PFAS
Sonoma County Public Health Laboratory
Santa Rosa, CA · about 30 miles
Certified for bacteria
Brelje and Race Laboratories, Inc.
Santa Rosa, CA · about 32 miles
Certified for bacteria, nitrate, lead and copper, metals, minerals and other inorganics, organic chemicals, disinfection byproducts
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 May 31, 2019 to Feb. 24, 2026, read Oct. 10, 2026
- Limits and goals: each contaminant’s page, with its EPA source.
- How this page is built: methodology.
PWSID CA1700519. Rebuilt from EPA data on Oct. 18, 2026.
What to do next
- Read up on the 4 results above a lineWhat each one does to health, where it comes from, and the certification claim that addresses it.Start with Haloacetic acids (HAA5)
- Get the utility’s own reportGolden State Water Company - South Shore 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