Drinking water is a recognized mode of transmission of various parasitic and bacterial infections and high prevalence rates of water-borne infection have been found during past studies in rural areas of the Nile Delta (Farag et al. 1979; Khairy. Barakat & Omar, 1978).

SUMMARYWhilst the major danger associated with drinking water is that it may be contaminated with sewage or human excreta, the danger of pollution from animals must not be overlooked. Outbreaks of infection from drinking water are frequently reported (Melnick & Gerba, 1979) and high prevalence rates of diarrhoeal diseases have been found in the Nile Delta (Sallamet al. unpublished data). The supply of potable water is a critically urgent national problem and is of especial importance to communities which must rely on poorly designed supply systems and which lack even the minimum quality control services.