Rural Water System #1 (RWS #1), Iowa’s first rural water system, was constructed in the mid‑1970s and now includes three treatment plants drawing from three water sources. Plant 1 uses the Hospers Well Field, a shallow alluvial aquifer near Sheldon, Iowa, while Plants 2 and 3 rely on shared groundwater sources near Sioux Center, Iowa, and Hudson, South Dakota. Due to the nature of the Hospers Well Field, Plant 1 was expected to eventually be classified as influenced groundwater (IGW), requiring more stringent treatment.

Need for Improvements
The IGW classification triggered a regulatory requirement for redundant filtration at Plant 1. Because Plant 1 supplies less than 20 percent of system demand, RWS #1 evaluated alternatives and selected a system‑wide solution rather than adding treatment at that location. Increasing capacity and redundancy at Plant 2 provided a more effective and flexible approach, strengthening overall system reliability and supporting future growth. DGR Engineering partnered with RWS #1 and the Iowa Department of Natural Resources to develop a compliant and strategic plan.

Solution and Outcome
At Plant 2, aging steel gravity filters—originally built in 1975 and expanded in 1992—were replaced to increase capacity from 1,850 gpm to 3,000 gpm and meet redundancy requirements. Horizontal pressure filters were selected to maximize the existing footprint and improve operational efficiency, including simplified ammonia removal. A phased construction approach maintained treatment capacity throughout the upgrade. The improvements delivered a cost‑effective, long‑term solution that enhanced reliability, met regulatory requirements, and advanced system capacity goals.