The use of calculators and computers in the wastewater field has come a long way in the past 30 years for use in calculating, computing, sorting, retrieving, and displaying data. An electric driven calculator was a rarity at a treatment plant in the late 1950’s. The next major step was the availability of a 4-function Texas Instruments calculator for report preparation. In Oregon, the use of the Apple microcomputer in wastewater treatment plants began approximately 6 years ago and since that time, the options and opportunities change monthly. The focus of this discussion will be on suggested uses for computers, what is available, how do you make intelligent hardware and software choices, and examples of computer applications. The current application of computers range from a 200,000 gallon a day plant using a Hewlett Packard programmable calculator with peripheral interface for making process control decisions to the plant with a main frame system that requires a full time programmer and controls on-line process control. This presentation covers the middle of the two extremes, with an emphasis on microcomputers such as the Apple, Apricot, IBM, Compaq, etc. The spectrum of users includes small and large plant superintendents, maintenance managers, lab personnel, and sewer billing departments as examples.