The International Association of Plumbing and Mechanical Officials (IAPMO) is seeking volunteers with a technical background in plumbing system design to participate on the Water Demand Calculator consensus body for the development of IAPMO Z1403.

The plumbing industry has long recognized that potable water systems in today’s buildings are oversized. This presents a growing health and safety concern, as problems associated with declining water quality have steadily increased in recent years with respect to water aging due to longer water residence times in plumbing systems. Responding to this need, IAPMO initiated a project to develop the Water Demand Calculator 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 1940s 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. This effort led to the introduction of the Water Demand Calculator to the 2018 Uniform Plumbing Code (UPC) in accordance with the ANSI-accredited development process.

The Water Demand Calculator has been widely accepted in such U.S. jurisdictions as Wisconsin, New Jersey, California, and Oregon, as well as in Canada with adoption in Vancouver. The Water Demand Calculator has also been recognized in the ASPE 2022-2023 Engineering Design Handbook as the recommended way to size residential buildings, the ASPE Engineering Methodology to Reduce the Risk of Legionella in Premise Plumbing, and the AWWA M22 Water Service and Water Meter Sizing Manual.

The development of this binational (ANSI/CAN) standard will provide jurisdictions and provinces with a standard accredited by both the American National Standards Institute (ANSI) and the Standards Council of Canada (SCC).

For more than 30 years, IAPMO has developed American National Standards, initially as the secretariat for the ANSI Z124 Technical Committee, and since 2005 as an ANSI-accredited standards development organization. On May 10, 2018, IAPMO received accreditation through SCC for development of National Standards of Canada, thus accepting the responsibility for development of CAN/IAPMO-designated standards. 

The Water Demand Calculator consensus body members will assist IAPMO with the development of this new American National Standard and National Standard of Canada. Consensus body members will operate in accordance with IAPMO’s accredited procedures for standards development: IAPMO/ASSE PP-1 (Policies and Procedures for Consensus Development of American National Standards) and IAPMO PP-2 (Policies and Procedures for Development of National Standards of Canada).

“This standard will be a guideline for pipe right-sizing that addresses decades of oversized piping design that has resulted in the unintended consequences of inflated system costs, degradations in water safety and wasted energy,” said John Higdon, IAPMO’s director of Standards Development.

The first consensus body meetings will be held virtually in September.

The deadline to apply is Sept. 27. Applications can be downloaded here: https://forms.iapmo.org/iapmo/committee/app_ps_committee.aspx

Industry stakeholders — including installers, manufacturers, plumbing professionals, building owners and managers, engineers, AHJs, and the general public — are invited and encouraged to apply to participate.