Microbial and Physico-Chemical Characteristics of Surface Water Sources Used on Dairy Farms in Ontario

Six surface water sources used to wash milking equipment and provide drinking water to the animals on dairy farms in Eastern Ontario were characterized for microbial and physico-chemical characteristics over a 16 month period. The water sources were selected because they had a history of microbial contamination and presented a wide selection of physico-chemical characteristics. Results are discussed with respect to available on-site disinfection technologies. Total and fecal coliforms were detected in over 90% of all water samples, Escherichia coli and Enterococcus spp. in 77%, Clostridium perfringens and Yersinia enterocolitica in about 50%, Campylobacter spp. in 36%, and Salmonella in 25%. For all pathogens, counts were highly variable, and maximum values were 1 to 2 orders of magnitude higher than the medians. On-site disinfection systems will have to be designed to deactivate the highest count of pathogens, thereby providing a conservative safety margin for most of the year. Disinfection technologies will also have to be selected based on physico-chemical characteristics of the water sources, especially the level of hardness, turbidity and UV transmittance which can adversely affect their effi ciency. On some farms, a pretreatment such as coagulation fl occulation will be necessary to make the surface water suitable for low-cost disinfection technologies.