The approval is based on data reported in a study commissioned by the Water Quality Association, titled "Analysis of Indoor Peak Demands in 60 Selected Single-Family Homes." Aquacraft Inc., a water engineering and management firm, conducted the study.

The current state plumbing code requires plumbers and installers to size POE water treatment equipment using traditional fixture unit value flow-rate calculations. When code design flow rates are too high, oversized POE water treatment devices, which are inefficient and more expensive, would be required by code.

According to the home water treatment industry, POE units operate efficiently between 7-10 gpm for sustained periods of time and can accommodate higher flows without sacrificing water treatment quality. The study results show that indoor flows rarely exceed 10 gpm, and then only for a few seconds.

The sizing method is valid through August 2007. The Wisconsin Plumbing Code Council may consider in 2003-2004 to permanently include the alternate sizing method in the state's plumbing code.