OK / Calvin
OK · Tap water records
Calvin tap water, in plain English
Here is what the EPA's own data shows about tap water in Calvin. According to EPA SDWIS data retrieved June 2026, Calvin is served by 1 active community water system, together reported to serve about 300 people.
As of June 2026, EPA records show 54 violations across the community water system(s) serving Calvin, going back to the earliest EPA record. 5 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
Calvin
300 served · groundwater · PWSID OK2003201 - Health-based Tetrachloroethylene: a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded 2 times between January 1996 and July 1996. The EPA record lists a level of 0.032 ; the limit (MCL) is 0 . All have since returned to compliance, per EPA records.
- Health-based Coliform (Pre-TCR): a health-based violation (a contaminant recorded above the limit the EPA tracks), recorded 3 times between April 1980 and November 1987. The EPA record lists a level of 5 ; the limit (MCL) is 1 . 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 14 times between July 2006 and July 2025. All have since returned to compliance, per EPA records.
- Monitoring Gross Alpha, Excl. Radon and U: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 2 times in April 2021. All have since returned to compliance, per EPA records.
- Monitoring Combined Uranium: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 2 times in April 2021. All have since returned to compliance, per EPA records.
- Monitoring Combined Radium (-226 and -228): a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 2 times in April 2021. All have since returned to compliance, per EPA records.
- Monitoring Gross Beta Particle Activity: a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 2 times in April 2021. All have since returned to compliance, per EPA records.
- Monitoring Nitrate-Nitrite: 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 Coliform (TCR): a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 5 times between July 1991 and May 2015. 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 January 2010 and July 2010. All have since returned to compliance, per EPA records.
- Monitoring Coliform (Pre-TCR): a monitoring or reporting violation (a required test or report was late or missed — not a measured exceedance), recorded 19 times between November 1979 and May 1982. 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 June 2026. Records cover the EPA's full reporting history for these systems. Verify at EPA ECHO.