The plumbing industry has long recognized that building potable water systems in today’s buildings are oversized. This presents a growing health and safety concern, as problems associated with declining water quality, such as Legionella, have been steadily increasing in recent years and are strongly correlated to water aging due to longer water residence times in plumbing systems.
Responding to this need, IAPMO initiated a project to develop the WDC to provide a new water supply sizing method that takes modern water usage patterns into account. It represents the first statistically based sizing method since the 1940’s and is a product of a multi-year research project between IAPMO, the American Society of Plumbing Engineers (ASPE), the Water Quality Research Foundation (WQ-RF) and the University of Cincinnati.
The impetus behind the development of the WDC is multi-faceted. Most importantly, and consistent with IAPMO’s imperative to address health and safety concerns as a priority, the WDC works to accurately predict water use patterns in residential buildings so that water pipes are properly sized, significantly reducing water aging in buildings. Use of the WDC also provides for faster hot water delivery times throughout the hot water systems. As such, it will also save energy, water, and reduce utility bills for the entire life of the plumbing system.
The WDC provides the above benefits while also working to reduce residential construction costs. This study provides estimates of probable cost for copper water piping and PEX water piping that were developed for each prototype. Estimates of probable costs were calculated for prototypes in the high cost New York City market, the medium cost Pittsburgh, PA market and the lower cost Oklahoma City, OK construction markets.
The results of the study indicate when the Water Demand Calculator is used, there are notable construction cost savings associated with each of the three residential prototype water service entrances, interior cold water mains / branches, interior hot water mains / branches, fittings, labor, and appurtenances.
