Here is what the EPA's own data shows about tap water in Mason. According to EPA SDWIS data retrieved October 2026, Mason is served by 1 active community water system, together reported to serve about 2,228 people.
As of October 2026, EPA records show 115 violations across the community water system(s) serving Mason, going back to the earliest EPA record. 84 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 Revised Total Coliform Rule: a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded once in April 2026. 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 Gross Alpha, Excl. Radon and U: a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded 32 times between July 2014 and October 2022. The EPA record lists a level of 16 PCI/L; the limit (MCL) is 15 PCI/L. All have since returned to compliance, per EPA records.
Health-based Combined Radium (-226 and -228): a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded 51 times between April 2009 and October 2021. The EPA record for these does not include a measured level. 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 2 times between November 2024 and February 2026. 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 3 times between December 2017 and December 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 2025. 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 22 times between January 2010 and August 2020. 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 3 times between October 2019 and December 2019. 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.