format, allowing fecal indicator bacteria such as E. coli and E. faecalis to be detected electrochemically without any sample pre-treatment. Since the colour of the detection compound is of no consequence, this allows detection in deeply coloured matrices. US EPA testing requirements In 1989 the U.S. Environmental Protection Agency (EPA) published its Total Coliform Rule (TCR) which imposed major monitoring changes for public water systems nationwide. The testing requirements under the 1989 TCR were more thorough than the previous requirements. The required number of routine coliform tests was increased, especially for smaller water utilities. The regulation also required automatic repeat testing from all sources that show a total coliform positive (known as triggered source water monitoring). In 2013 EPA revised the TCR, with minor corrections in 2014. See also Coliform bacteria Coliform index Indicator bacteria References Additional resources EPA. "Monitoring and Assessing Water Quality: Fecal Bacteria." Enterobacteria Feces Water quality indicators