The article describes results of a study to use expert systems technology in a water utility. The three-year study has resulted in the development of computerized expert systems whose basic principles should be broadly applicable to other water utilities. The system described in the article, called a customer query expert system, is designed to assist administrative personnel in handling customers' inquiries and complaints about water quality. The system has been developed as a prototype and will be placed in field operation for further testing and refinement in the near future. Significant effort, however, is expected to be necessary to move from prototype 'proof-of-concept' demonstrations to fully featured systems that are of practical use in the field.