Since 1988, the Department of Environmental Protection has been conducting detailed evaluations of the state's surface water treatment plants. The on-going program, called Filter Plant Performance Evaluation (FPPE), is a method of determining the effectiveness of a drinking water treatment plant in removing disease-causing organisms from the incoming raw water. The program also helps to ensure that public water systems are correctly monitoring water quality information as well as helping to reduce violations.
The evaluation process combines a thorough on-site survey of filter plant operations, equipment and water quality conditions. Additionally, the process includes the use of complex, specialized equipment to assess plant performance. It also involves sampling the facility's raw and filtered water for later microscopic evaluation in the Department of Environmental Protection’s laboratory. Although FPPEs capture a "snapshot" of filter plant performance, they also entail review of monitoring records to gain a long-term picture. Pennsylvania is one of only a handful of states conducting these types of extensive filter plant evaluations.