The Pittsburgh Water and Sewer Authority (PWSA) owns and operates the existing 120 mil gal (452 ML) open reservoir in Highland Park, known as Highland Reservoir 1. It provides drinking water for approximately 50% of Pittsburgh's residents. In 1984, changes in drinking water regulations required public water suppliers in Pennsylvania to cover, abandon, or otherwise protect open potable water reservoirs from potential contamination. This article describes how PWSA resolved the issue, under intense public and political scrutiny, by building a new microfiltration plant housed in a small and attractive nineteenth century‐style building that integrates well with the park atmosphere and the surrounding community. The process used by the engineering consultant to pilot‐test for the ideal treatment process is discussed.