Appendix M of the IAPMO Uniform Plumbing Code, or the Water Demand Calculator, was integrated into the California Plumbing Code on July 1. It provides a new method for sizing water pipes in residential buildings. For Villara Corp., a leading plumbing and HVAC contractor in Northern California, it remains business as usual, having used the calculator for over five years to construct over 5,000 single-family homes.

The IAPMO Water Demand Calculator has faced challenges due to exclusions from its documentation and calculations, causing difficulties for engineers in luxury apartment buildings.

The Water Demand Calculator consensus body members will assist IAPMO with the development of this new American National Standard and National Standard of Canada. 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.

On May 8th, I presented at the LADWP La Kretz Innovation Center for the ASPE LA Chapter on California’s adoption of the Water Demand Calculator. I spoke about the intersection of water and energy, emphasizing their crucial link in modern civilization.

AWWA M22 is a manual of water supply practices that covers the basic principles and methods of water distribution system design and operation.

The alternative approach will be available for statewide use on a voluntary basis starting July 1.

The Water Demand Calculator has been adopted in several states and cities, including California and Seattle, and is expanding peak flow rate calculations into commercial buildings. The future looks bright as version 3.0 is in the works for commercial buildings.

While the basic template of version 2.1 of the calculator remains intact, version 2.2 includes several new features. 

The primary cost savings are associated with reduced diameter water service entrances, interior cold water mains/branches, interior hot water mains/branches, fittings, labor, and appurtenances.