(3) Perform the studies under subdivisions (1) and (2) on a minimum of five percent (5%) of all total coliform-positive samples, except for those methods where verification or confirmation or both is already required, for example, the M-Endo and LES Endo Membrane Filter Tests, Standard Total Coliform Fermentation Technique, and Presence-Absence Coliform Test. Methods for establishing false-positive and negative-rates may be based on lactose fermentation, the rapid test for [BETA]-galactosidase and cytochrome oxidase, multi-test identification systems, or equivalent confirmation tests. False-positive and false-negative information is often available in published studies or from the manufacturer, or both.
1 Lactose broth, as commercially available, may be used in lieu of lauryl tryptose broth, if the PWS conducts at least twenty-five (25) parallel tests between this medium and lauryl tryptose broth using the water normally tested, and this comparison demonstrates that the false-positive rate and false-negative rate for total coliform, using lactose broth, is less than ten percent (10%).2 If inverted tubes are used to detect gas production, the media should cover these tubes at least one-half (1/2) to two-thirds (2/3) after the sample is added.3 No requirement exists to run the completed phase on ten percent (10%) of all total coliform-positive confirmed tubes.4 MI agar may also be used*.5 Six-times formulation strength may be used if the medium is filter-sterilized rather than autoclaved.6 The OPNG-MUG test is also known as the Autoanalysis Colilert System.7 The Colisure Test may be read after an incubation time of twenty-four (24) hours. *The methods referenced in this section may be obtained as follows:
(1) Methods 9221A, 9221B, 9222A, 9222B, 9222C, 9221D, 9223, and 9221E may be found in "Standard Methods for the Examination of Water and Wastewater", 1992, American Public Health Association, et al., 18th edition, or "Standard Methods for the Examination of Water and Wastewater", 1995, American Public Health Association, et al., 19th edition, available from the American Public Health Association, et al., 1015 Fifteenth Street N.W., Washington, D.C. 20005.(2) A description of the Colisure test may be obtained from IDEXX Laboratories, Inc., One IDEXX Drive, Westbrook, Maine 04092.(3) The minimal medium ONPG-MUG test may be found in "National Field Evaluation of a Defined Substrate Method for the Simultaneous Detection of Total Coliforms and Escherichia coli from Drinking Water: Comparison with Presence-Absence Techniques", (Edberg, et al.), Applied and Environmental Microbiology, Volume 55, pages 1003-1008, April 1989.(4) Preparation and use of MI agar is set forth in the article, "New Medium for the Simultaneous Detection of Total Coliforms and Escherichia coli in Water" by Brenner, K.P., et al., 1993, Applied and Environmental Microbiology, 59:3534-3544, and errata published in Applied and Environmental Microbiology, 59:4378. Also available from the Office of Water Resource Center (RC-4100), 401 M. Street S.W., Washington, D.C. 20460, EPA/600/J-99/225.(5) A description of the E*Colite® test, "Presence/Absence for Coliforms and E. coli in Water", December 24, 1997, is available from Charm Sciences, Inc., 36 Franklin Street, Malden, Massachusetts 02148-4120.(6) A description of the m-ColiBlue24® test, August 17, 1999, is available from the Hach Company, 100 Dayton Avenue, Ames, Iowa 50010. These methods are available for review at the Indiana Department of Environmental Management, Office of Legal Counsel, 100 North Senate Avenue, Thirteenth Floor, Indianapolis, Indiana 46204.