A three-year cooperative agreement between the North Penn Water Authority (NPWA), Lansdale, Pennsylvania, and the US EPA Drinking Water Research Division, Concinnati, Ohio, to study use of expert systems technology in a water utility, has resulted in the development of two expert systems that demonstrate basic principles that should be broadly applicable to other water utilities. A 'customer query expert system' assists non-technical users in handling customer questions relating to water quality. A 'pump efficiency watcher' expert system is designed to flag long-term changes in well pump performance, and to calculate a number of pump performance parameters of interest. The results clearly demonstrate that expert systems that are potentially useful to water utilities can be developed at moderate cost. Significant effort, however, should be expected to move from prototype 'proof of concept' expert system demonstrations, to fully-featured, field-usable products.