What must an Arizona public water system do after a coliform-positive test?

Read the complete report with the responsible operator and laboratory. Record the sample identifier, location, collection time, reported organism and when the system received notification. A total-coliform-positive result is not automatically an E. coli maximum-contaminant-level violation, but it still initiates required action.

ADEQ's current Revised Total Coliform Rule page describes a find-and-fix approach to sanitary defects. Do not treat a later clean result as a reason to hide the original event. Confirm whether the system's result, repeats or other history triggers an assessment, public notice or additional work.

This is a regulated-system response. A commercial private well classified as a public water system has duties different from a homeowner collecting an informational sample. The sanitary-survey preparation guide covers a separate scheduled system review.

ADEQ says a routine total-coliform-positive result requires three repeat samples at the original, upstream and downstream sites specified in the Microbiological Sample Siting Plan. For groundwater systems, it also identifies raw-water source sampling from sources that were active and contributed to the finished water when the original positive sample was taken. Have the operator and laboratory apply the relevant source-sampling requirements, rather than sampling every convenient faucet.

The sample-siting-plan guide explains how those named taps and map locations are documented. For a system serving 1,000 people or fewer with a confirmed assessment trigger, the Level 1 or Level 2 assessment guide covers the separate find-and-fix review without extending the immediate sampling deadlines.

Its current instructions require repeat and triggered samples within 24 hours of laboratory notification. If a weekend or holiday affects laboratory availability, contact the authority for an accepting laboratory; do not assume the deadline pauses.

For an E. coli-positive result, ADEQ calls for contact by the end of the business day, or within 24 hours if the business day has already ended. Notify the system's Compliance Assistance Coordinator and follow its instructions for results and the sampling plan. Obtain the actual notice and consumer-use instructions when required; a positive finding should not be converted into an improvised public message.

Keep the original and repeat reports, notification times, sample locations, operating conditions and authority directions. Document assessments, identified defects, corrective work and verification separately. Work with qualified personnel on treatment or repairs; this checklist does not provide disinfectant doses or authorize tank entry.

Public-notice records and the certified operator agreement help keep communication and responsibility clear. A repaired pipe does not itself complete the regulatory response.