“As engineers, we were going to be in a position to change the world — not just study it.” — Henry Petroski

2024 has officially started, and most of us have an idea of some initial goals for the beginning of the year. For 2024, right-sizing the water supply looks to continue to be a central topic. IAPMO created the Water Demand Calculator Task Force in 2011, and working in conjunction with the University of Cincinnati (UC) and the American Society of Plumbing Engineers (ASPE), created a new peak flow calculator for single- and multi-family residential applications. This update, which was released in the 2018 Uniform Plumbing Code (UPC), represented the first revision of peak flow rate calculations in almost 80 years. Since then, IAPMO has continued to grow the Water Demand Calculator program and is actively working on expanding peak flow rate calculations into commercial buildings.

Adoption of the Water Demand Calculator

As of this writing, the Water Demand Calculator has been adopted in several states including Hawaii, Montana, Nevada, New Jersey, New Mexico, North Dakota, Oregon, Washington, and Wisconsin, as well as the cities of Beaumont and Houston, Texas; Foster City and San Jose, California; Seattle; and even Vancouver, British Columbia, Canada. However, 2024 will bring even more remarkable adoptions of the Water Demand Calculator.

  • As the fifth-largest economy in the world, California will officially adopt Appendix M: the Water Demand Calculator on July 1. The Water Demand Calculator was proposed for adoption during the 2022 Intervening Cycle by the Department of Housing and Community Development (HCD) and the Statewide Utility Codes and Standards Team. In response to a petition received from stakeholders, HCD did the research, held workshops, and ultimately adopted and further amended Appendix M to be a voluntary option for single- and multi-family dwellings. The California Water Efficiency Partnership (CalWEP) — a state chapter of the Alliance for Water Efficiency (AWE), of which IAPMO is a member — and 15 member agencies supported the petition. IAPMO will collaborate on a presentation with LADWP to the ASPE LA Chapter at La Kretz on May 8 to further educate California.
  • Seattle, likely the first city to adopt the Water Demand Calculator, has officially mandated the usage of Appendix M for R-2 Occupancies (multi-family) to help promote energy and water conservation. This is the first known jurisdictional adoption that requires the usage of the Water Demand Calculator. IAPMO will host a training on utilizing the Water Demand Calculator for multi-family applications at Green River College on Feb. 17. Stay tuned for more details.
  • Northern Georgia, which includes the Atlanta Metro Area, has adopted the Water Demand Calculator as an “acceptable design method” from the IAPMO/ANSI 2020 Water Efficiency and Sanitation Standard for the Built Environment, “which accounts for the demands of water-conserving plumbing fixtures, fixture fittings, and appliances.” Furthermore, the ordinance allowing usage of the Water Demand Calculator states: “If a future version of the Peak Water Demand Calculator, including other building types such as commercial, such updated versions shall be an acceptable design method.” IAPMO will host a webinar to discuss the adoption in Northern Georgia in early February.

This update, which was released in the 2018 Uniform Plumbing Code (UPC), represented the first revision of peak flow rate calculations in almost 80 years.

The future is bright for right-sizing with the Water Demand Calculator

Speaking of future versions of the Water Demand Calculator, version 3.0 is in the works for commercial buildings. As was shared at the 2023 Water Demand Calculator Virtual Summit in November, IAPMO is working with industry partners to acquire the data for commercial buildings, ranging from hotels to health care facilities to offices to schools to retail, among others. If you or your firm want to get involved, either by volunteering time or helping us network with clients to install sensors in their buildings, please consider signing up for the Water Demand Calculator Task Group, which has swelled to about 50 members: IAPMO Innovation Task Group Membership Application

As 2023 has shown us, the Water Demand Calculator is the gold standard for the right sizing of plumbing systems. More and more jurisdictions continue to adopt this groundbreaking tool in an effort to improve energy and water conservation. This is leading to more in-person and virtual training opportunities (including the 2024 Water Demand Calculator Virtual Summit, which is scheduled for Nov. 12, 2024), continued growth of the Water Demand Calculator into commercial buildings and a continued increase in awareness about the cost, sustainability and water quality benefits of right-sizing via the Water Demand Calculator. 2024 looks to continue the momentum that IAPMO started in 2011.