The Lancashire Cryptosporidium event of 2015 - lessons learned for the water industry

摘要

In August and September 2015 a major drinking water quality emergency occurred in north Lancashire, when more than 700,000 consumers in Blackpool, Preston, the Fylde Coast and surrounding areas were required to boil their water. This was in response to the detection of Cryptosporidium oocysts in water supplied from Franklaw water treatment works, at a maximum detected concentration of 0.119 oocysts per 10 litres, a level never previously recorded at the works. The source of the oocysts was later found not to have arisen from the source water, but from a planned change to the motive water arrangements for chlorination, bringing contaminated water from a service reservoir into the later stages of the works bypassing treatment designed to remove Cryptosporidium. The absence of a risk assessment, the use of a reservoir for process water post-treatment, the recycling of water within the works and the restarting of the works after contamination was discovered, were all in contravention of good practice identified in the reports of the group of experts published during the 1990s. Had the recommendations of these reports been followed, the consequences of the incident could have been much reduced, and it may have been avoided completely.