Plumbing and Water Efficiency

Addressing water scarcity is imperative for policymakers.

From both a public health and cost-savings perspective, water conservation is of the utmost importance. The city of Los Angeles is projected to save $2 billion over 10 years since retrofitting bathrooms with water-saving fixtures in the more than 600 Department of Water and Power (LADWP) owned buildings.

It’s important, though, that the water flow provides adequate hand and body cleaning, as well as sufficient waste removal. Pipe sizing needs to be adequate to the long-term system performance without being excessively overbuilt to avoid this unintended consequence.


Plumbing systems in new home construction are routinely overbuilt because the most commonly-used pipe sizing formula is almost 90 years old–well before today’s low-flow fixtures and appliances came on the scene. IAPMO did the math to update Hunter’s Curve for the reality of today’s water-efficient fixtures and appliances.

Water usage is best standardized by putting in place strong Uniform Plumbing Codes that take on the power of law. Comprehensive and easy-to-enforce Uniform Plumbing Codes ensure that homes and buildings embody the most efficient and safest plumbing systems.

As emerging water technologies enter the marketplace, frequent and collaborative plumbing code revisions help public health departments keep pace with technology. IAPMO invests heavily in original research around pipe sizing, drain line carry, rainwater harvesting and the impact of reduced flow fixtures.