SINCE 1966, Philadelphia has been using computers to maintain proper operational records, keep abreast of the condition of our mechanical equipment, furnish information for the design of future plants, and to apply mathematical disciplines to analytical data which would otherwise be impractical. Since we can now look back on 5 years' experience with computers, we are in a position to review and evaluate their usefulness. Even though we have itemized the many uses that we have made of the computer, we really had two main objectives in mind; one, to reduce the paper work required in record keeping of large treatment facilities; and, two, pave the way for the eventual instrumentation and automation of the treatment facilities. Our first project which we termed Datamation was to prepare a program which would enable the daily tabulation of all of the data collected from the various operator and laboratory log sheets. We found that each day, 384 pieces of information were recorded at our Northeast Water Pollution Control Plant. By means of suitable programming, a monthly report was generated which tabulated all the above data and performed all the necessary calculations including desired statistical analyses. This program is called NELOG (GffARINO and RADZIUL, 1968). The program included provisions for data screening and subsequent rejection. From this monthly report, the computer generates a monthly summary. The twelve summaries are also combined by the computer into an annual report. These three programs reduce the technical and clerical record keeping time, minimize human errors, and give us better and more readily accessible data. An outgrowth of the operationally oriented NELOG was a maintenance based data logging report termed MEDICO (GuARINO and CARPENTER, 1970). This program, established in 1969, lists the condition of every large piece of equipment at the Northeast Treatment facility. MEDICO serves as a management tool to evaluate, control and direct maintenance in waste treatment. An excerpt from MEDICO is presented in TABLE 1. The City of Philadelphia has embarked on a $200-million program to improve its treatment plant facilities. In the Delaware Valley drainage area, all municipalities and industries has been allocated a fixed quantity of carbonaceous biochemical oxygen demand as well as suspended solids which they would be permitted to discharge into the receiving stream. To enable the proper design of the proposed treatment facilities to meet these effluent requirements, data available in the memory of the computer has been statistically analyzed and furnished to the designer. This, of course, is not a new technique but simply one of the many advantages that the computer makes available to us. We expect this information to be extremely useful in the design of the new treatment facilities. The first of such reports Variations of Input Parameters at the Northeast Water 597