OKLAHOMA CITY, OK — The Oklahoma Uniform Building Code Commission (OUBCC) has unanimously approved the adoption of IAPMO's Uniform Plumbing Code (UPC®) Appendix M—the Water Demand Calculator®—as an alternative method for sizing water supply piping in single-family and multifamily residential buildings.

The provision will become available for voluntary statewide use beginning Sept. 14 and will be incorporated into Chapter 6 of Oklahoma's adopted International Plumbing Code.

Alternative Sizing Method Reflects Modern Water Use

The Water Demand Calculator provides a science-based approach for estimating peak residential water demand based on modern plumbing fixtures and actual water use patterns. Unlike traditional sizing methods developed decades ago, the calculator is designed to reduce oversized water piping, which can increase installation costs and contribute to water stagnation.

Properly sized plumbing systems can also improve water quality by reducing conditions that promote bacterial growth, including Legionella, while lowering water heating energy use and helping reduce a building's overall carbon footprint.

The OUBCC establishes minimum statewide building standards, while local jurisdictions may adopt more stringent requirements if desired.

Modern Design Option for Plumbing Professionals

“IAPMO appreciates the Oklahoma Uniform Building Code Commission for recognizing the value of modern pipe-sizing methods that improve both public health and water efficiency,” said Christina Kaeini, IAPMO Senior Director of Government Relations, who testified before the commission in support of the proposal. “The Water Demand Calculator gives designers another science-based option that reflects today’s plumbing fixtures and water use patterns while helping reduce construction costs, conserve water and energy, and improve water quality within premise plumbing systems. We’re grateful to the commission, stakeholders, and our industry partners for their thoughtful consideration and support.”

The Water Demand Calculator represents the culmination of years of research aimed at developing a statistically based methodology that more accurately reflects current residential water demand.

Oklahoma Joins Growing List of Adopting States

With the adoption of Appendix M, Oklahoma becomes the 11th state to recognize the Water Demand Calculator, joining California, Hawaii, Montana, Nevada, New Jersey, New Mexico, North Dakota, Oregon, Washington and Wisconsin.

The methodology has also been adopted by several major cities, including Houston, San Jose, Seattle and Vancouver, British Columbia.

To learn more visit iapmo.org.