Source document
Calvin, OK 2017 Consumer Confidence Report
The original annual drinking-water report. Every number on the Calvin, OK water quality page is pulled from this document.
The Calvin, OK figures for 2017 come from EPA's national Safe Drinking Water database (SDWIS / ECHO) — not a single utility-published PDF. Every value on the Calvin, OK water quality page is transcribed from that public dataset, and you can verify it against the same source below.
View the source dataset ↗https://echo.epa.gov/tools/data-downloads/sdwa-download-summary