ESDU 08002 is a practical User Guide to the occurrence, mitigation and removal of fouling in fresh water systems and on the design of such systems to minimize the consequences of fouling. Here, "fresh water" is defined as natural or treated water with low salt content. This User Guide is a companion to ESDU 03004 on seawater fouling. Developed under the guidance of the IHS ESDU Oil Industry Fouling Working Party, its objective is to provide the designer and the operator of both onshore and offshore equipment with a ready and practical User Guide to fresh water fouling problems encountered in the oil and other industries. ESDU 08002 introduces fresh water fouling as it affects heat transfer in various types of heat exchanger. The principal types of fouling (crystalline, biological, particulate and corrosion) and the effect on their fouling mechanisms of key factors such as velocities and temperatures are described and illustrated. Often, these fouling mechanisms operate at the same time and interact and this type of interaction is discussed. The selection of the materials of construction for the heat exchangers and associated equipment is often crucial as are overall and detailed design considerations and guidance on these matters is provided. Fouling in fresh water systems is all pervasive and most systems require specific on-line mitigation measures. These include chemical and mechanical methods and the use of anti-fouling coatings. Detailed discussion is presented on the range of mitigation strategies. If fouling cannot be controlled at acceptable levels by the use of good design practice and appropriate mitigation measures, then the heat exchange equipment must be periodically cleaned to maintain adequate performance. Cleaning methods can include chemical and mechanical means, and these are described. The importance of designing for cleaning is stressed. An extensive list of selected references is given.