UNITED STATES ENVIRONMENTAL PROTECTION AGENCY GUIDANCE FROM HOTLINE COMPENDIUM WSGH35 Date Issued: August 1991 SUBJECT: Reporting Confluent Growth on Total Coliform Samples SOURCE: Paul Berger (202) 260-3039 Title 40 CFR sections 141.21(g) and 141.32 contain requirements for analytical methodology and reporting under the Total Coliform Rule. Is confluent bacterial growth considered a violation of the rule and how would it be reported? Response: If one or more total coliform colonies are detected, the sample must be reported as total coliform-positive. If no coliforms are detected, the laboratory must invalidate the sample (see 40 CFR 141.21 (c) (2)). The regulations do not specifically address how confluent growth (with no detected coliforms) is to be reported, but the laboratory may record the sample as "confluent growth." ------- |