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State Water Resources Control Board <br /> Division of Water Quality <br /> GAMA Program <br /> ANALYTICAL INFORMATION <br /> Analytical Description The US EPA has approved several methods to test for the <br /> presence of total coliform bacteria. These methods <br /> include Multiple Tube Fermentation (MTF), membrane <br /> filtration (MF), and enzyme substrate tests. Testing <br /> methods for E. coli verification follow these same basic <br /> methodologies. Tests for E. coli may be conducted in lieu <br /> of fecal coliforms, when allowed. <br /> Additional tests (not listed below) are available for bacteria <br /> (e.g., Enterococci) that are not part of the coliform group <br /> and for potentially harmful proterozoa such as <br /> Cryptosporidium and Giardia. The presence/absence of <br /> coliform bacteria is used as a bacteriological indicator for <br /> the presence of additional harmful microorganisms. <br /> Repeat analyses that test for the presence of fecal <br /> coliform or E. coli are required upon detection of total <br /> coliforms. <br /> Method Detection Limits Some total coliform and E. coli tests are presence or <br /> absence only. MPN methods may provide a robust <br /> estimate based upon statistical derivation. <br /> Known Limitations to Interference from heterotrophic (harmless background) <br /> Analytical Methods bacteria may occur. High total dissolved solids (TDS) <br /> may interfere and result in false positives. <br /> Methods Method Technology Type Target <br /> EPA Method 1604 Membrane Filtration Total coliform and E. coli <br /> SM3 9223B Enzyme Substrate Total coliform and E. coli <br /> SM 9221 F Multiple Tube Fermentation E. coli <br /> SM 9221 B Multiple Tube Fermentation Total coliform <br /> SM 9221G Multiple Tube Fermentation E. coli <br /> 2MPN = Most Probable Number of coliform <br /> 3SM = Standard Method <br /> Revised September, 2019 3 <br />