Risk assessment for Cryptosporidium parvum in reclaimed water

The risk of cryptosporidiosis associated with San Franciscoʹs proposed water reclamation program is conservatively estimated using an exponential dose–response model based on human infectivity data for Cryptosporidium parvum. The observed C. parvum concentrations in filtered secondary effluent present less than a 1-in-10,000 annual risk of contracting the water-borne disease through regular exposure at parks and golf courses irrigated with tertiary reclaimed water in San Francisco.