This paper provides an introduction to the theory and analytical  methods of forecasting industrial water use. Two basic approaches to the problem are presented--forecasting with and without the  use of demand functions for water. Section 2 discusses the widely  used water use coefficient method and regression techniques for forecasting  water use. Section 3 reviews the statistical and economic-engineering models for deriving industrial water demand functions. Section 4  illustrates how water demand functions can be utilized in forecasting exercises and discusses the difficulties of forecasting industrial  water use.