The Disinfection Forum has been running as a collaborative project (CP404) since March 2010 with 9 participating water companies. The aim of the project is to provide a platform for review of issues, research and regulatory perspectives on all aspects of disinfection.
An issue discussed at each of the meetings was chlorination policy and implementation. Under Regulation 26 (England) and Regulation 27 (Wales), Water Companies need to implement a risk based approach to disinfection that provides sufficient evidence to the Drinking Water Inspectorate (DWI) to demonstrate the effectiveness of their policies. It needs to take account of pathogens expected to be present in each water supply system, and include specification for chlorine concentration and contact times the basis of the Ct concept, to deal with site specific risk. There is no specific guidance from DWI on Ct, and discussions at the Disinfection Forum indicated that companies are using a range of approaches and Ct values.
This work is continuing into a second year, based around development of a “Ct toolbox” to identify appropriate disinfection conditions in an objective and logical manner. This will use the best available evidence to help companies to develop a robust policy that stands up to regulatory scrutiny. It will provide a greater consistency to developing and implementing Ct between participating companies, because the approach is based on the same disinfection data and common assumptions, and therefore presents a more consolidated approach. The intention is to develop a framework to allow companies to justify their existing policy and make changes if appropriate.
The Ct toolbox will allow water companies to establish and implement a robust Ct policy strengthened by a common approach and shared knowledge, providing greater confidence that public health is not being placed at undue risk.
Further details are available from Tom Hall on +44 (0) 1793 865065 or email tom.hall@wrcplc.co.uk.