Everyone is preoccupied with oil shortages these days. But the building industry’s eyes are already on the next scarce natural resource: water.

While the U.S. population nearly doubled between 1950 and 2000, the demand for water more than tripled, according to the EPA, putting pressure on both water supplies and an aging distribution system. That’s true not just in arid states, but across the map. A recent government survey showed that at least 36 states are expecting shortages by 2013.

Water is intertwined with energy, too, since water supply and treatment plants consume about 56 billion kWh per year—enough electricity to power more than 5 million homes for a year.

Bath faucets and showerheads are undergoing a sea change as the EPA’s new low-flow standards begin to take effect. Last fall, its WaterSense program—the plumbing equivalent of Energy Star—began certifying lav faucets that only use a maximum 1.5 gpm, a 20% reduction from the federal standard of 2.2 gpm. Shower-head specs are slated to follow early next year.

Faucets

To earn the WaterSense label, bath faucets must pass a third-party test proving that they not only use less water but also function as well as their less-efficient counterparts. To maintain a solid level of performance, WaterSense set a high and low spec ranging from 1.5 gpm at 60 psi to 0.8 gpm at 20 psi. (Psi varies based on a home’s distance from the pumping station and the number of homes using it.)

“A faucet is a fairly simple device; there’s only so much you can do with it,” says Shawn Martin, technical director at the Chicago-based Plumbing Manufacturer’s Institute (PMI). “The WaterSense studies showed that flows less than 0.8 at 20 psi didn’t provide the level of performance the consumer expected. Their intent is on making sure the WaterSense logo comes to stand for water savings and decent performance.”

In anticipation of the certification, plumbing manufacturers have been testing the appeal of low-flow fixtures for several years. Virtually every major manufacturer has converted its lav faucets to 1.5 gpm or less or will do so by the end of this year, without accompanying price increases.

Paul Patton, senior product manager at Delta Faucet, says his company’s tests showed that consumers didn’t notice the difference between standard and water-efficient bath faucets until the flow rate reached 1.0 gpm. “That doesn’t mean we won’t look at other technologies to see if we can deliver additional water conservation,” he says.

To achieve a satisfying flow at 1.5 gpm or less, faucet aerators now typically include a pressure-compensating device. It delivers a heavier water force, letting users rinse the toothpaste out of their brushes without running the water longer, which would counteract the savings. The technology also helps calibrate the flow to differing water pressure levels.

“A rubber O ring is squeezed into grooves in the flow plate, like a juicer with holes,” explains Jerry Capasso, wholesale bath product manager for Moen. “It gives a very consistent flow rate over a wide range of pressures.”

Showerheads

Showerhead performance is trickier to quantify. People’s preferences for how a shower should feel vary widely, and the EPA is still trying to define basic parameters such as shower force and spread, and how well the droplets adhere to the skin’s surface. The predicted goal is a maximum flow of 2.0 gpm at 60 psi, down 20% from the standard 2.5 gpm.

Two problems typically afflicting low-flow showerheads are cold spots caused when too much air is introduced into the stream, and the pins-and-needles effect created when water is unevenly dispersed through the nozzles.

For the most part, manufacturers are addressing these issues by changing the shape or pattern of the spray nozzles and water droplets, and by controlling the pressure. Kohler, for example, redesigned the traditional showerhead cavity that uses the force of gravity to deliver water. The new technology uses an internal turbine and flow restrictor, combined with the optimal nozzle count and positioning, to create a rejuvenating spray, whether it’s 2.5 gpm or 1.75 gpm. Last year, Hansgrohe rolled out showerheads that use air-injection technology to add pressure and increase the volume of the droplets while gushing at 1.8 gpm.

Another challenge is automatic compensating valves, which traditionally have been designed for a 2.5-gpm flow rate and may not work as well with low-flow units. PMI is working with WaterSense to also address standards for the valves.

“The key thing we’re telling builders is to make sure the valves and showerheads match if they’re being purchased separately,” Martin says. “If the valve literature doesn’t say it’s compatible with showerheads down to [a certain specified] flow, we recommend contacting the manufacturer to ask.”

The jury is still out on the commercial success of WaterSense bath fixtures. But with the benefit of better technology and rigorous independent testing, the EPA expects the standards will quickly become the new normal.

“The purpose of WaterSense is market transformation, like Energy Star,” says Birute Vanatta, product manager at Eastern Research Group, the EPA’s WaterSense contractor. “Once a product hits mainstream, we won’t label it anymore.”

Cheryl Weber is a freelance writer in Lancaster, Pa.