This report outlines the findings from a collaborative study into 'Cell culture sensitivity and assessment of ultraviolet light inactivation of cryptosporidium under realistic water treatment conditions' initiated by representatives of the Drinking Water Inspectorate (DWI), United Kingdom Water Industry Research (UKWIR), the American Water Works Association Research Foundation (AwwaRF), the United States Environmental Protection Agency (US EPA), Kiwa and the Water Services Association of Australia (WSAA). The research programme identified and assessed using 'blind trials' an optimum cell culture technique that is suitable for routine use in disinfection studies and general risk assessment.
Potential changes to the UK Drinking Water Quality Regulations could make Cryptosporidium inactivation using UV the most cost-effective treatment option in many situations. UV disinfection is well established in water tratment in the UK and elsewhere. There is now a substantial body of evidence to indicate that UV can provide high levels of inactivation of Cryptosporidium at doses typically used for water treatment disinfection. Turbidity below the regulatory limit of 1 NTU should not impair the disinfection performance of UV. Other water quality factors that could impair UV performance by affecting absorbance of UV or fouling of lamps can be dealt with effectively through operational control systems.
The report provides information and guidance on implementation of UV disinfaction to inactivate Cryptosporidium, based on a review of regulations and standards from other countries, particularly the USA.
This report details an investigation into the relationship between farm re-stocking and cryptosporidia. The study took place following the foot and mouth disease (FMD) related cull within the River Caldew catchment, Cumbria. The effects of restocking on the species and subtypes of Cryptosporidium in farmed livestock, wild animals and surface waters, were compared with isolates from farms that had been continually stocked.
Field studies took place in two phases with the aim of taking samples before and after re-stocking. Whilst differences were observed between the phases, the prevalence of Cryptosporidium oocysts in the catchment was similar. This may be related to the rapid restocking of the catchment following the FMD cull and the relative resistance of Cryptosporidium in the environment during the de-stocked period.
This report can also be accessed on the FWR website.