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January 10, 2013
MCL eliminated for total coliform

In its first revision of the 1989 federal Total Coliform Rule (TCR), the EPA is endeavoring to bring the rule’s requirements up to speed with the current science on pathogens in drinking water.  The TCR is the only microbial drinking water regulation that applies to all public water systems (PWSs).  As with the TCR, the revised TCR (RTCR) will affect approximately 154,000 PWSs, according to the Agency.  Compliance with the new requirements is required beginning April 1, 2016. 

E. coli is prime indicator

Primarily, the new action eliminates both the maximum contaminant level goal (MCLG) and the maximum contaminant level (MCL) for total coliform and replaces these with an MCLG and MCL for E. coli.  According to the Agency, the change is in line with recommendations made in 2008 by the Total Coliform Rule Distribution System Advisory Committee.  The committee was formed by the EPA and comprised 15 stakeholder organizations, including the EPA, state and tribal representatives, utility associations, and advocacy groups for the environment, public health, epidemiology, and consumers.  

The EPA notes that E. coli is superior to total coliform as an indicator of fecal contamination and the potential for harmful pathogens.  “Many of the organisms detected by total coliform methods are not of fecal origin and do not have any direct public health implication,” states the EPA.  The acute total coliform MCL violation in the 1989 TCR has been maintained as the MCL for E. coli under the RTCR. 

Treatment for coliforms

The RTCR will still require a “treatment technique” for coliforms that requires assessment and corrective action.  Specifically, a PWS that exceeds a specified frequency of total coliform occurrence must conduct an assessment to determine if any sanitary defects exist and, if found, correct them.  In addition, a PWS that incurs an E. coli MCL violation must conduct an assessment and correct any sanitary defects found. 


The RTCR maintains the monitoring requirements of the TCR while adjusting the monitoring frequencies.  For example, the RTCR lists criteria that well-operated small systems must meet to qualify for reduced monitoring; requires that monitoring be increased for high-risk small systems with unacceptable compliance histories; and establishes new monitoring requirements for seasonal systems such as campgrounds and some state and national parks.

Also, the RTCR eliminates the requirement that the PWS provide the public with monthly notices based on only the presence of total coliform.  Instead, the revision requires public notification when an E. coli violation occurs.

Click here for the final RTCF.