The Incidence of Cryptosporidium and Giardia in Private Water Supplies in the United Kingdom

Investigations into the microbiological quality of private water supplies have shown deterred quality, particularly during periods of heavy rainfall. The majority of investigations has been of short duration and the range of microorganisms examined has been restricted to faecal indicators. This chapter presents a study on the incidence of Cryptosporidium and Giardia in private water supplies in the United Kingdom. Seven private water sites were selected across the UK. The water at the majority of the sites was of poor microbiological quality. Large increases in fecal indicator bacteria, the presence of Campylobacter and large increases in Cryptosporidium as well as Giardia correlated with periods of heavy rainfall. Either side of the rainfall event counts were low or absent. Treatment installed at private water supply sites needs to be designed to cope with poor microbiological quality during adverse weather conditions.