In 1992, congress reduced the maximum water consumption level of toilets from 3.5 gallons per flush to 1.6, and opponents were hopping mad. Plumbing contractors and consumers railed that the new toilets were ineffective and wasted water due to multiple flushes.

These critics were more or less accurate, but that was then. Fast forward 16 years and manufacturers have stepped up their game. Today’s toilets perform exceedingly well. Now change is afoot once again.

The federal government warns that population growth and persistent drought will force at least 36 states into water shortages by 2013. Water conservation is now a national priority, which is why the EPA launched the voluntary WaterSense program to make it easy for consumers to identify and purchase water-efficient products. High-efficiency toilets were recently added to the program.

A high-efficiency toilet (HET) flushes with 20 percent less water than a standard unit. Such toilets may meet the criteria in one of two ways: A single-flush toilet must use no more than 1.28 gallons per flush, or a dual-flush unit must have a full flush using no more than 1.6 gallons and a reduced flush that uses no more than 1.1.

Some manufacturers are exceeding this standard. Lincolnwood, Ill.–based Gerber Plumbing Fixtures has introduced an Ultra Flush 1.1-gallon toilet that uses pressurized air to decrease the amount of water required for a flush.

In addition to dual-flush units, Kohler, Wis.–based Kohler offers the San Raphael Pressure Lite, a one-piece unit that uses 1.0 gallon per flush.

“This toilet represents the future of flushing technology,” Kathryn Streeby, director of marketing for Kohler’s sanitary products, said in a press release. “The industry is progressing to better technology and improved performance while utilizing less water.”

With toilet flushing consuming about 30 percent of all domestic water use, ­manufacturers say they are committed to the water conservation movement. The question that looms, however, is whether or not that movement will make voluntary standards become law. With the eco-movement gaining steam, it very well could, so be prepared.

Wise Guy: The FloWise toilet can be flushed in two ways: a traditional 1.6 gallons per flush or a water-saving 0.8 gallons per flush. It has a two-piece design, an elongated bowl, and a concealed trap for a slim profile. Available in white, it comes in a standard height or a comfort height.  American Standard. 800-899-2614.

Ultra low: Exceeding federal standards, the Ultra Flush uses 1.1 gallons of water per flush. The pressure-assisted unit uses the standard water supply to pressurize the air inside the tank, which forces water into the bowl. It’s available in a variety of styles, colors, and rough-in sizes. Gerber Plumbing Fixtures. 630-754-0278.

Royal flush: The San Raphael flushes with just 1 gallon of water, which could save a family of four between 7,000 gallons and 10,000 gallons of water per year versus the standard 1.6-gallon unit. Measuring 21 1/2 inches high, the one-piece unit features an elongated bowl and a 12-inch rough-in. It comes in seven colors. Kohler. 800-456-4537.

Smart Start: Unlike most dual-flush toilets, Sydney Smart offers a 0.8 gallon flush and an optional 1.28 gallon flush instead of a 1.6. Based on usage estimates, it averages .89 gallons per flush and is designed to save a family of four up to 2,975 gallons of water per year over other high-efficiency toilets. It comes in white and biscuit. Caroma USA. 503-681-2720.