This article is an extended summary of the report prepared by the Process Water Subgroup of the European Hygienic Engineering and Design Group (EHEDG). This guideline is part of a series of three on Process Water. Originally published in April 2004, it is the 27th in the series of EHEDG summaries published in TIFS. The full report was prepared by A.M. van Buren (Chairman), J.A. Milligan, H.M.J. van Eijk, J.O' Brien, A.Winkler, D. Lawrence, R. Hopman and W.G.J.M. van Tongeren and is available from CCFRA at pubs@campden.co.uk. Information about EHEDG can be found at www.ehedg. org. The production of EHEDG Guidelines is supported by the European Commission under the Quality of Life Programme, Project HYFOMA (QLK1-CT-2000-01359). It is strongly recommended that for application in the field, operators in the food industry should read the guideline in its entirety, to ensure a holistic approach.