Periodic sanitary surveys are required for all systems collecting fewer than 5 samples per month, see Table 5-F3. Systems need not take any additional samples beyond those normally required. If fecal coliforms or E. cold are detected, the system must notify the State before the end of the same business day, or if determined after the State office is closed, by the end of the next business day. This is an acute violation of the MCL for total coliforms. State invalidation of a total coliform-positive sample invalidates subsequent fecal coliform of E. cold positive results on the same sample.
Heterotrophic bacteria can interfere with total coliform analysis.
In such case, EPA recommends using media less prone to interference from heterotrophic bacteria for analyzing the replacement sample. Analytical Methodology a. A 100 ml standard sample volume must be used in analyzing for total coliforms, regardless of the analytical method used. Fecal coliform analysis must be conducted using methods described in 40 CFR 141.21 and Standards Methods. Sodium and Corrosivity.