The challenge: Tackling the problem of microorganisms and pesticides

摘要

"The disinfection of public water supplies is a statutory requirement in England and Wales. Water supplied for domestic or food production purposes must not contain any micro-organism or parasite at a concentration which could constitute a potential danger to human health." So says the Drinking Water Inspectorate's (DWI) Guidance on UV disinfectioni. The phrase "micro-organism or parasite" includes, of course, Cryptosporidium which is still a major challenge to the water industry. There are several reasons for this, not least of which is the notorious resistance of the protozoan to the most widely used disinfectant, chlorine. The situation is not helped by the fact that monitoring Cryptosporidium is not easy and, even if it were, the Water Supply (Water Quality) Regulations give little guidance on acceptable levels. Regulation 29 of the 2000 Regulations required that "the average number of Cryptosporidium oocysts per 10 litres of water is less than one". This required a physical barrier.