More Energy Savings at Stake When Plumbing Code Gets Updated

The national model plumbing code published by the International Code Council is due for an update this year, and it could make a difference on how much energy new homes use.

Showers use nearly 40% of the hot water in homes. New changes to the model plumbing code would require more efficient showerheads that save water and energy while preserving comfort and cleaning power.

Credit: Photo by Geoffrey Fairchild

The national model plumbing code published by the International Code Council (ICC) and adopted by states and cities is due for an update this year, a process that may not be on the radar of most advocates for energy efficiency and community sustainability. But it could make a difference on how much energy new homes use. 

Energy vs. plumbing codes

During 2019 and 2020, much progress was made to improve the ICC’s 2021 version of the International Energy Conservation Code, when state and local officials overcame builder objections and voted to approve a slate of climate-friendly upgrades to the model code that localities choose whether to adopt and enforce for new construction and extensive renovations. Although builder appeals voided some of these advancements, the remaining improvements will substantially improve the efficiency of new homes built to the code, as noted by my colleague Lauren Urbanek here.

The ICC’s upcoming plumbing code revisions offer a bit of unfinished business for sustainability advocates because any change in the efficiency of showerheads was left untouched in the recent batch of energy code improvements. Following a vote by the ICC’s membership to include efficiency requirements for showerheads in the 2018 IECC, the organization’s Board of Directors vacated the membership’s action, ruling that any standards relating to showerheads must be addressed exclusively in the plumbing code. So here we are.

NRDC and partners, including the City of Scottsdale, AZ, the Salt River Project (an integrated water and power utility serving Phoenix), and well-known green building analyst Dave Collins, have proposed to amend the plumbing code to improve showerhead efficiency by 20 percent.  The code currently allows a maximum flow rate of 2.5 gallons per minute (gpm), while our joint proposal would set this cap at 2 gpm. The proposal is in two parts, with one revising the plumbing chapter of the International Residential Code, which covers one- and two-family homes, and the other amending the International Plumbing Code, which most states use for commercial buildings. The upshot is that there will be two separate votes on whether to set higher standards for showerheads during this code revision cycle.

The U.S. Environmental Protection Agency's voluntary WaterSense program adopted the 2 gpm specification back in 2010, along with performance criteria that ensure adequate spray pattern, spray force, and usable flow at locations with low water pressure. Today, more than 10,000 models from over 200 brands meet all WaterSense specifications, demonstrating the widespread availability and commercial viability of efficient showerheads. In many models, built-in pressure compensation ensures that showerheads deliver a strong spray of water even in buildings with low water pressure, so there's nothing keeping people from enjoying their showers while using the most water-efficient products.

How much can efficient showerheads save?

Efficient showerheads save energy, because showers account for about 40% of hot water use in homes.  Even accounting for several states that already require efficient showerheads, the potential further savings from a 2 gpm requirement are substantial.

If all newly installed showerheads nationwide met the WaterSense specification beginning in 2025 (the earliest practical application of the 2024 plumbing code now under development), the U.S. would save large amounts of water and energy while avoiding at least 38 million metric tons of carbon dioxide emissions through 2050, according to the supporting analysis behind a November 2020 report by the Appliance Standards Awareness Project. These cumulative greenhouse gas reductions would equate to the average emissions from 10 coal plants in a year. In 2035, efficient showerheads would save nearly 80 billion gallons of water annually, adding up to 1.7 trillion gallons of cumulative savings by 2050. Annual energy savings in 2035 will reach 4.1 terawatt hours and $1.9 billion, respectively. By 2050, consumers will have saved a whopping $41.4 billion in total on utility bills. Although all showerhead sales are not covered by code requirements, these savings estimates offer a glimpse at the order of magnitude of savings in new construction and renovations covered by the code.

Of course, even as we seek a more efficient plumbing code, the harebrained showerhead rule rushed out by the Trump administration last December still must be dealt with. As described here, Trump’s Department of Energy (DOE) literally changed the definition of “showerhead” so that multi-nozzle heads can use virtually unlimited amounts of water. Fortunately, the new administration quickly took notice, and targeted the showerhead rule (Item 4 on this February 19 DOE memo) along with others for review. The Trump rule is unlikely to survive, and should be relegated to the trash heap long before the publication of the 2024 plumbing code.

The proposed update to the ICC’s plumbing codes link directly to a core purpose of the code: establishing minimum requirements to advance safety, health, and general welfare through affordability and energy conservation. Nothing is more fundamental to health, safety, and general welfare than maintaining adequate water supplies and reducing planet-warming air pollution. It's time to finalize this long-overdue upgrade.

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