CA / Hollister
CA · Tap water records
Hollister tap water, in plain English
Here is what the EPA's own data shows about tap water in Hollister. According to EPA SDWIS data retrieved June 2026, Hollister is served by 21 active community water systems, together reported to serve about 53,795 people.
As of June 2026, EPA records show 111 violations across the community water system(s) serving Hollister, going back to the earliest EPA record. 38 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.
What the EPA has on record, by system
Hollister, City Of
26,017 served · surface water · PWSID CA3510001 - Health-based TTHM: a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded 17 times between October 2015 and July 2022. The EPA record lists a level of 0.083 MG/L; the limit (MCL) is 0.08 MG/L. All have since returned to compliance, per EPA records.
- Monitoring TTHM: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 4 times in April 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Total Haloacetic Acids (HAA5): a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 4 times in April 2024. EPA records do not show all of these as returned to compliance.
Sunnyslope County Water Dist
24,954 served · surface water · PWSID CA3510003 As of June 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.
Rancho San Joaquin Mwc
914 served · groundwater · PWSID CA3500581 - 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 Arsenic: a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded 4 times between October 2022 and July 2023. The EPA record lists a level of 0.011 MG/L; the limit (MCL) is 0.01 MG/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 Public Notice: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 2 times in April 2024. All have since returned to compliance, per EPA records.
- Monitoring Total Haloacetic Acids (HAA5): a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in January 2021. All have since returned to compliance, per EPA records.
- Monitoring TTHM: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in January 2021. All have since returned to compliance, per EPA records.
- Monitoring Revised Total Coliform Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in February 2018. 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 3 times in October 2017. All have since returned to compliance, per EPA records.
- Monitoring Consumer Confidence Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in July 2012. All have since returned to compliance, per EPA records.
Casa De Fruta Water System
250 served · groundwater · PWSID CA4300611 - 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 Coliform (TCR): a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded once in July 1994. The EPA record for these does not include a measured level. All have since returned to compliance, per EPA records.
- 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.
Csa No. 31 Stonegate Ws
230 served · surface water · PWSID CA3500006 - Health-based CARBON, TOTAL: a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded 3 times in April 2022. The EPA record for these does not include a measured level. EPA records do not show all of these as returned to compliance.
- Monitoring Revised Total Coliform Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 5 times in July 2023. 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 2 times in October 2016. All have since returned to compliance, per EPA records.
San Justo Mutual Water Company
160 served · groundwater · PWSID CA3500550 - 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.
- 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 Consumer Confidence Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in July 2021. 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 3 times in January 2020. All have since returned to compliance, per EPA records.
- Monitoring TTHM: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 2 times in January 2020. EPA records do not show all of these as returned to compliance.
- Monitoring Public Notice: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in September 2007. All have since returned to compliance, per EPA records.
Hollister Ranch Estates
150 served · groundwater · PWSID CA3500904 - Health-based Combined Uranium: a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded 8 times between October 2015 and July 2017. The EPA record lists a level of 22 PCI/L; the limit (MCL) is 20 PCI/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 3 times in April 2023. EPA records do not show all of these as returned to compliance.
- Monitoring Revised Total Coliform Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 2 times between May 2017 and November 2019. All have since returned to compliance, per EPA records.
- Monitoring E. COLI: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in April 2017. All have since returned to compliance, per EPA records.
- Monitoring Public Notice: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in April 2010. All have since returned to compliance, per EPA records.
Rosa Morada Mutual Water Company
138 served · groundwater · PWSID CA3500549 - Monitoring Consumer Confidence Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 2 times between July 2003 and July 2012. All have since returned to compliance, per EPA records.
Ashford Highlands Mwc
132 served · groundwater · PWSID CA3500900 As of June 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.
Dunneville Estates Csa #50
120 served · groundwater · PWSID CA3500910 As of June 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.
Mcmahon Road Mutual Water Company
102 served · groundwater · PWSID CA3500510 - Monitoring Consumer Confidence Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in July 2006. All have since returned to compliance, per EPA records.
Comstock Mutual Water Company
100 served · groundwater · PWSID CA3500912 As of June 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.
Union Heights Mwc
98 served · groundwater · PWSID CA3500825 - Monitoring Consumer Confidence Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in July 2006. All have since returned to compliance, per EPA records.
Vineyard Estates Mwc
90 served · groundwater · PWSID CA3500579 - Monitoring E. COLI: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in July 2024. EPA records do not show all of these as returned to compliance.
- Monitoring Revised Total Coliform Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 4 times between June 2017 and August 2021. All have since returned to compliance, per EPA records.
- Monitoring Consumer Confidence Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in July 2002. All have since returned to compliance, per EPA records.
Creekbridge Mutual Water Company
69 served · groundwater · PWSID CA3500911 - 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 2025. EPA records do not show all of these as returned to compliance.
Valenzuela Water System
55 served · groundwater · PWSID CA3500527 - Health-based Nitrate-Nitrite: a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded 2 times between April 2018 and May 2018. The EPA record lists a level of 11 MG/L; the limit (MCL) is 10 MG/L. EPA records do not show all of these as returned to compliance.
- Monitoring Revised Total Coliform Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 5 times between March 2020 and May 2025. EPA records do not show all of these as returned to compliance.
- Monitoring CHROMIUM, HEX: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 2 times in April 2025. EPA records do not show all of these as returned to compliance.
- Monitoring Consumer Confidence Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 4 times between July 2002 and July 2009. 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 November 2005. All have since returned to compliance, per EPA records.
Casa De Fruta Orchards
53 served · groundwater · PWSID CA3500511 - Monitoring Revised Total Coliform Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in January 2022. All have since returned to compliance, per EPA records.
Venture Estates Mwc
50 served · groundwater · PWSID CA3500552 - Monitoring TTHM: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in August 2025. EPA records do not show all of these as returned to compliance.
- Monitoring Total Haloacetic Acids (HAA5): a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in August 2025. EPA records do not show all of these as returned to compliance.
- Monitoring Consumer Confidence Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in July 2007. All have since returned to compliance, per EPA records.
Springwood Estates Mwc
50 served · groundwater · PWSID CA3500575 - 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.
Whispering Pines Inn
38 served · groundwater · PWSID CA3500810 - Monitoring Revised Total Coliform Rule: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 4 times between February 2024 and April 2024. EPA records do not show all of these as returned to compliance.
San Benito County Water District
25 served · surface water · PWSID CA3510007 As of June 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.
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 June 2026. Records cover the EPA's full reporting history for these systems. Verify at EPA ECHO.