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Cryptospondium (part 1 of 2) Page 10 of 13 .8- � �9 major concern regarding its use. Due to its powerful oxidizing ability, it breaks down the naturally occurring organic matter in water, causing it to become a nutrient source for bacteria. It is possible, then, that the use of ozone, while inactivating Cryptosporidium, could stimulate the growth of bacteria in the distribution system. Some of these bacteria may cause disease, particularly in immunocompromised individuals. Filtration Removal of Cryptosporidium by �Itration is approximately 99 percent or 2 logs of reduction. Although levels as high as 99.9 percent or 3 logs of reduction have been reported. At times oocysts can be detected in filtered water; their breakthrough can be attributed to a variety of factors, including: ■ Increases in source water concentrations of Cryptosporidium. ■ Recycling filter washwater in the plant enabling concentrated slugs of Cryptosporidium to pass through the filters. ■ Operational factors such as improper filter washing, rapid flow changes, improper coagulation, etc. • Most waterborne Cryptosporidium outbreaks have been associated with operational problems rather than inherent treatment deficiencies. Regulatory Stance The regulatory stance varies considerably. The activities of the United Kingdom Drinking Water Inspectorate, the United States Environmental Protection Agency, the California Department of Health Services, and Canadian Authorities are summarized below. United Kingdom Regulatory authorities in the United Kingdom have the most extensive experience with the issue because of the number of outbreaks experienced. Their stance on Cryptosporidium is summarized in two major documents: The Badenoch Report entitled "Cryptosporidium in Water Supplies" (July 1990) and the Drinking Water Inspectorate's report "Cryptosporidium in Water Supplies: Progress With the National Research Program" (]uly 1992). The basic recommendation of these reports is that water treatment plants need to optimize their practices with respect to coagulation, filtration, and recycling of filter washwater. The Drinking Water Inspectorate is leading an aggressive research program to address the major research needs. EPA Cryptosporidium was not regulated under the 1989 Surface Water Treatment Rule due to the uncertainties surrounding Cryprosporidium (i.e., virulence, infedive dose, inactivation, etc.). Source monitoring for Cryptosporidium will be required sometime in 1996 under the Information Collection Rule (ICR). Methodological difficulties with the detection method have slowed down promulgation of the ICR though monitoring finally http://sfwater.org/printContent.cfm/C_ID/446/ 10/19/2004 r _ ... _ . ... _