ESDU 88024 considers scaling@ corrosion@ biofouling and particulate deposition and discusses the variables of importance for each. Advice is given on the design and subsequent operational management of a plant to minimise fouling. The importance of the water source@ and hence its composition@ is emphasised. Test equipment for assessing fouling is described. A table of heat transfer fouling resistances@ showing their dependence on temperature@ water velocity@ material and water treatment applied@ will be of particular value. Various means of fouling control are considered@ using chemicals and biocides as appropriate. The properties of biocides currently used in industrial applications are discussed. On-line mechanical cleaning methods are also considered.