Here is what the EPA's own data shows about tap water in Riverdale. According to EPA SDWIS data retrieved October 2026, Riverdale is served by 3 active community water systems, together reported to serve about 3,376 people.
As of October 2026, EPA records show 89 violations across the community water system(s) serving Riverdale, going back to the earliest EPA record. 82 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.
Health-based Arsenic: a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded 30 times between April 2006 and April 2014. The EPA record lists a level of 0.047 MG/L; the limit (MCL) is 0.01 MG/L. All have since returned to compliance, per EPA records.
Health-based Coliform (TCR): a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded 4 times between August 1992 and September 2013. The EPA record for these does not include a measured level. 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 2016. 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 between January 1998 and October 2013. All have since returned to compliance, per EPA records.
Lanare Community Services Dist
540 served · groundwater · PWSID CA1000053
Health-based TTHM: a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded once in January 2021. The EPA record lists a level of 0.2 MG/L; the limit (MCL) is 0.08 MG/L. All have since returned to compliance, per EPA records.
Health-based Arsenic: a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded 39 times between July 2007 and July 2018. The EPA record lists a level of 0.017 MG/L; the limit (MCL) is 0.01 MG/L. 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 2009. All have since returned to compliance, per EPA records.
Monitoring Arsenic: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded once in January 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 July 1993. All have since returned to compliance, per EPA records.
Terra Linda Farms
80 served · surface water · PWSID CA1009222
Health-based Total Haloacetic Acids (HAA5): a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded 4 times between January 2017 and October 2017. The EPA record lists a level of 0.091 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 3 times between October 2014 and April 2017. The EPA record lists a level of 0.09 MG/L; the limit (MCL) is 0.08 MG/L. All have since returned to compliance, per EPA records.
Health-based Surface Water Treatment Rule: a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded once in March 2012. The EPA record for these does not include a measured level. 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.