Here is what the EPA's own data shows about tap water in Paso Robles. According to EPA SDWIS data retrieved October 2026, Paso Robles is served by 11 active community water systems, together reported to serve about 35,782 people.
As of October 2026, EPA records show 68 violations across the community water system(s) serving Paso Robles, going back to the earliest EPA record. 55 of these are classified by the EPA as health-based (a contaminant recorded above the limit the EPA tracks); the rest are monitoring or reporting violations. Each is listed by system below, with its status.
Monitoring E. COLI: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in June 2015. All have since returned to compliance, per EPA records.
Heritage Ranch Csd
2,956 served · surface water · PWSID CA4010012
Health-based Total Haloacetic Acids (HAA5): a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded 13 times between October 2019 and January 2024. The EPA record lists a level of 0.067 MG/L; the limit (MCL) is 0.06 MG/L. All have since returned to compliance, per EPA records.
Health-based TTHM: a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded 2 times between October 2022 and January 2023. The EPA record lists a level of 0.086 MG/L; the limit (MCL) is 0.08 MG/L. All have since returned to compliance, per EPA records.
Walnut Hills Mutual Water Co
486 served · groundwater · PWSID CA4000670
As of October 2026, EPA records show no reported violations for this system in the period covered. This is not a guarantee about every substance, or about the water inside your home's plumbing.
Los Robles Mobile Home Estates
420 served · groundwater · PWSID CA4000649
As of October 2026, EPA records show no reported violations for this system in the period covered. This is not a guarantee about every substance, or about the water inside your home's plumbing.
Green River Mutual Water Co.
350 served · groundwater · PWSID CA4000554
Health-based LEAD AND COPPER RULE REVISIONS: a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded once in October 2024. The EPA record for these does not include a measured level. EPA records do not show all of these as returned to compliance.
Health-based Selenium: a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded once in October 2021. The EPA record lists a level of 140 UG/L; the limit (MCL) is 50 UG/L. EPA records do not show all of these as returned to compliance.
Monitoring LEAD AND COPPER RULE REVISIONS: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in October 2024. EPA records do not show all of these as returned to compliance.
Monitoring Lead and Copper Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in October 2017. All have since returned to compliance, per EPA records.
Monitoring Nitrate: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in January 2017. All have since returned to compliance, per EPA records.
Snake River Resort
150 served · groundwater · PWSID ID3370030
As of October 2026, EPA records show no reported violations for this system in the period covered. This is not a guarantee about every substance, or about the water inside your home's plumbing.
Resthaven Mobile Home Park
99 served · groundwater · PWSID CA4000654
Health-based Selenium: a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded 21 times between October 2020 and March 2026. The EPA record for these does not include a measured level. EPA records do not show all of these as returned to compliance.
Rancho Salinas Mbwc
50 served · groundwater · PWSID CA4000803
Monitoring Nitrate: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in January 2020. All have since returned to compliance, per EPA records.
Monitoring Lead and Copper Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in January 2018. All have since returned to compliance, per EPA records.
Almira Water Association
40 served · groundwater · PWSID CA4000631
Health-based Arsenic: a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded 14 times between January 2020 and April 2024. The EPA record lists a level of 18 UG/L; the limit (MCL) is 10 UG/L. All have since returned to compliance, per EPA records.
Monitoring Nitrate: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in January 2023. All have since returned to compliance, per EPA records.
Monitoring Lead and Copper Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 2 times between October 2017 and October 2021. All have since returned to compliance, per EPA records.
Monitoring Coliform (TCR): a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in April 2006. All have since returned to compliance, per EPA records.
Mustang Springs Mutual Water
30 served · groundwater · PWSID CA4000775
Health-based Fluoride: a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded 3 times between July 2016 and October 2022. The EPA record lists a level of 2.8 MG/L; the limit (MCL) is 2 MG/L. All have since returned to compliance, per EPA records.
Monitoring Lead and Copper Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in July 1993. All have since returned to compliance, per EPA records.
Ada'S Lodges
25 served · groundwater · PWSID CA4000839
Monitoring Lead and Copper Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 2 times between January 2023 and October 2023. All have since returned to compliance, per EPA records.
What this means
A health-based violation means a contaminant was recorded above the limit the EPA tracks for it. A monitoring or reporting violation means a required test or report was late or missed — not that a contaminant was measured above a limit. “Returned to compliance” means the EPA recorded the issue as resolved.
This page summarizes the EPA's own records and does not assess whether your water is safe to drink. For the most current details, you can verify every record directly with the EPA, and contact your water system with questions.
Source: U.S. EPA Envirofacts SDWIS, retrieved October 2026. Records cover the EPA's full reporting history for these systems. Verify at EPA ECHO.