Ocotillo Oasis, LLC
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
- 96 people
- Connections
- 55
- Water source
- Groundwater
- Based in
- San Marcos, CA
- County
- San Diego
- Owner
- Private
- Hardness
- Soft
The ZIP code it serves
The short answer
2 results are above the health goal. The worst: Nitrate, above the health goal. 16 health-based violations since 2016.
What handles itWhat was found
Nitrate, fluoride, arsenic and chromium (total): California’s own results, samples taken from Jan. 21, 2020 to June 9, 2026, with EPA’s 2012 to 2019 file for earlier years.
Uranium: EPA’s compliance monitoring file, samples taken from June 13, 2017 to June 13, 2017. Newer results are in the utility’s annual water quality report.
Above the health goal2
Nitrate
Comes from the source
21ppm
Highest sample; found in 87 of 116
2026 average: 2.7 ppm
From 2021 to 2026, 10 samples were above EPA’s legal limit of 10 ppm, the highest 21 ppm in 2022. The next sample at the same point, within 30 days, kept the average above the limit for one; nine have no follow-up sample on file within 30 days. 10 ppm is also EPA’s health goal. In 2026, the latest year on file, its 10 samples averaged 2.7 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 25 ppm, in 2018, and EPA recorded a violation in 2019.
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
0.23ppb
Highest yearly average, 2017
Averaged by year, the highest was 0.23 ppb, in 2017: below EPA’s legal limit of 30 ppb, but above its health goal of zero. Its highest single sample was 0.54 ppb. That is the only year on file.
What handles it
- NSF/ANSI 58 look for “Uranium”
Below EPA’s limits1
Fluoride
Forms or is added in treatment
3.5ppm
Highest yearly average, 2020 to 2026
2026 average: 1.7 ppm
Averaged by year, the highest was 3.5 ppm, in 2023, below EPA’s legal limit of 4.0 ppm. Its highest single sample was 5.3 ppm. In 2026, the latest year on file, its five samples averaged 1.7 ppm. EPA recorded no violation for fluoride at this utility since 2020. Earlier, from 2012 to 2019, EPA’s file shows a highest yearly average of 4.6 ppm, in 2017, and EPA recorded violations in 2013, 2014, 2015, 2016 and 2017.
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
- Chromium (total)
- Lead
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
Soft, typically 9.5 mg/L (0.6 grains per gallon), across 3 sampling points, 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
| Contaminant or rule | Type | Period | Measured | Status |
|---|---|---|---|---|
| Fluoride | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Jan. 1, 2024 to March 31, 2024 | 2.0 MG/L | Archived |
| Fluoride | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | April 1, 2023 to June 30, 2023 | 3.0 MG/L | Archived |
| Fluoride | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Jan. 1, 2023 to March 31, 2023 | 2.3 MG/L | Archived |
| Fluoride | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Oct. 1, 2021 to Dec. 31, 2021 | 2.2 MG/L | Archived |
| Fluoride | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | July 1, 2021 to Sept. 30, 2021 | 2.5 MG/L | Archived |
| Fluoride | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | April 1, 2021 to June 30, 2021 | 2.3 MG/L | Archived |
| Fluoride | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Jan. 1, 2021 to March 31, 2021 | 2.4 MG/L | Archived |
| Nitrate | A sample was above the legal limit, for a contaminant judged one sample at a time.EPA: Maximum Contaminant Level Violation, Single Sample | Sept. 3, 2019 to Oct. 31, 2019 | 27 MG/L | Resolved |
| Fluoride | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Oct. 1, 2017 to Dec. 31, 2017 | 4.8 MG/L | Resolved |
| Fluoride | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | July 1, 2017 to Sept. 30, 2017 | 4.8 MG/L | Resolved |
| Fluoride | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | April 1, 2017 to June 30, 2017 | 4.6 MG/L | Resolved |
| Fluoride | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Jan. 1, 2017 to March 31, 2017 | 4.7 MG/L | Resolved |
| Fluoride | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Oct. 1, 2016 to Dec. 31, 2016 | 4.8 MG/L | Resolved |
| Fluoride | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | July 1, 2016 to Sept. 30, 2016 | 4.6 MG/L | Resolved |
| Fluoride | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | April 1, 2016 to June 30, 2016 | 4.7 MG/L | Resolved |
| Fluoride | The running average was above the legal limit.EPA: Maximum Contaminant Level Violation, Average | Jan. 1, 2016 to March 31, 2016 | 5.2 MG/L | Resolved |
| Health-based violations only. Resolved and archived mean the utility returned to compliance or the state closed the record. 60 monitoring or reporting violations not shown. | ||||
What this report can’t tell you
Everything else. Nitrate, fluoride, arsenic and chromium (total) 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. Ocotillo Oasis, LLC’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 Jan. 21, 2020 to June 9, 2026; EPA’s compliance samples are from June 13, 2017 to June 13, 2017.
Testing your own tap
The 3 labs California certifies closest to the area Ocotillo Oasis, LLC serves, in a straight line. Call first: certification is test by test, and not every lab takes samples from homeowners.
Brawley Analytical, Inc.
Brawley, CA · about 35 miles
Certified for bacteria, minerals and other inorganics
Imperial County Public Health Laboratory
El Centro, CA · about 40 miles
Certified for bacteria
Babcock Laboratories, Inc.
El Centro, CA · about 40 miles
Certified for bacteria
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 March 29, 2021 to Dec. 18, 2024, read Oct. 10, 2026
- Limits and goals: each contaminant’s page, with its EPA source.
- How this page is built: methodology.
PWSID CA3700291. 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 reportOcotillo Oasis, LLC 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