This paper reviews the routine and periodic systems used to clean food equipment. The manner in which soil accumulates on surfaces, and factors affecting that accumulation are discussed. The mechanisms by which microbial development on the equipment surface is controlled by the system is also discussed. The contamination sequence of deposition, attachment, depletion, growth and contamination by the organism is presented in detail. Changes in surface microbial numbers over time are reviewed for system components and complete systems. The relationship between the amount of soil on the surface and microbial survival is examined. The ability of the routine and periodic systems to control soil accumulation and microbial development is discussed. Factors affecting design of a cleaning system are also presented. These factors are used to design a cleaning system, using a pipeline milking machine as an example.