Pacific Institute Endorses IAPMO Water Demand Calculator as Key to National Water Efficiency

ONTARIO, CA — The International Association of Plumbing and Mechanical Officials (IAPMO®) announced that its Water Demand Calculator® has been recognized as a key recommendation in a new report from the Pacific Institute, Untapped Potential: An Assessment of Municipal and Industrial Water Efficiency Potential in the United States.

The national assessment finds that improved efficiency could reduce municipal and industrial water use across the country by 25–60%, saving billions of gallons daily while cutting energy and infrastructure costs. Among its top recommendations, the Pacific Institute calls for broad adoption of IAPMO’s Water Demand Calculator to right-size plumbing systems, reducing structural water waste and improving water quality.

Report Urges Adoption of IAPMO’s Design Tool

The report states:

“States and municipalities should amend their plumbing codes to require IAPMO’s Water Demand Calculator for estimating peak demand and provide training on its use for inspectors, installers, and design professionals.”

A nonpartisan research organization, the Pacific Institute advances water sustainability and resilience through science-based policy and partnerships that promote efficient, equitable water management.

Research Collaboration Underscores IAPMO’s Leadership

Christoph Lohr, IAPMO’s Vice President of Technical Services and Research, served on the report’s Advisory Group and contributed research cited throughout the study.

“It’s an honor to see the Pacific Institute recognize the transformative potential of the Water Demand Calculator,” Lohr said. “By rethinking how we size plumbing systems, we’re not only saving water but also cutting construction costs, improving energy efficiency, and enhancing public health through better water quality. This report reinforces what we at IAPMO have long believed—smart plumbing design is foundational to sustainable water management.”

Aligning Plumbing Design with Real-World Use

Developed through years of technical research and collaboration with industry partners, IAPMO’s Water Demand Calculator enables engineers and designers to estimate peak water demand more accurately in residential and multifamily projects. By matching system design to actual usage patterns instead of outdated sizing methods, the tool helps reduce pipe diameters, minimize stagnation, and boost overall system efficiency.
Learn more: iapmo.org/we-stand/water-demand-calculator.

Report Outlines Major Efficiency Potential

The Untapped Potential report offers a data-driven roadmap for policymakers, utilities, and industry professionals to implement proven water-saving solutions. Among its key findings:

• Existing technologies and practices could save 14.0 to 34.1 million acre-feet annually—equivalent to 12.5 to 30.4 billion gallons daily, or a 25–60% reduction in municipal and industrial use.

• Households represent the greatest water-saving opportunity, but commercial and institutional facilities also offer meaningful reductions.

• Leak repair in water delivery systems remains one of the largest and most cost-effective—yet underfunded—opportunities.

• Water efficiency can lower costs, reduce energy use, and strengthen infrastructure, yet is often underprioritized compared to new supply projects.

“By reducing leaks and adopting proven technologies and practices, we can save tens of millions of acre-feet of water each year—enough to dramatically reduce pressure on lakes, rivers, and aquifers while also supporting a vibrant economy and resilient communities,” said Heather Cooley, Chief Research and Program officer at the Pacific Institute. “We’re excited to see this research helping to reframe efficiency as one of the most powerful and practical tools for building a sustainable water future.”

The full report is available from the Pacific Institute at pacinst.org/publication/untapped-potential-municipal-and-industrial-water-efficiency-potential-in-the-united-states.

The Institute will host a webinar on Dec. 4 to discuss the report's findings. To register, visit us06web.zoom.us/webinar/register/WN_LeeTRynaQT2lzp-nIFVf1w#/registration.