Most Water-Efficient Toilets

Some new toilets use 1.28 gallons or less per flush

High efficiency toilets (HETs) use less water than standard 1.6-gallons-of-water-per-flush (gpf) toilets -- many ring in around 1.28 gallons or less. In fact, HETs that display the U.S Environmental Protection Agency's WaterSense label have been certified as having a maximum flush volume of 1.28 gallons and the ability to remove at least 350 grams of solid waste per flush. Several hundred toilets have qualified for the WaterSense label thus far. Some municipalities even offer consumers a rebate for buying one.

High-efficiency toilets are stuck with some negative perceptions, such as lacking power or the water necessary to keep the bowl clean, however that is not necessarily the case in testing. Some HETs have proven to be just as powerful as 1.6 gpf toilets, removing as much as 1,000 grams of solid waste in independent testing. The downside: Most are expensive compared to standard 1.6 gpf toilets like the Toto Drake CST744S (*Est. $255).

The American Standard Compact Cadet 3 FloWise 2403.128 (*Est. $390) is one high-efficiency toilet that, despite low water use, removed 1,000 grams of solid waste in Maximum Performance (MaP) Testing sponsored by 22 organizations in the U.S. and Canada. It's also the top-rated low-water-use toilet in one professional review that performed both solid waste and liquid waste tests. Many may prefer the taller rim height on this toilet, which meets the standards of the Americans with Disabilities Act (ADA). Although this toilet includes an antimicrobial glaze that helps keep the bowl clean, the flush wasn't as effective at bowl cleaning as some other toilets in one review. However, cleaning behind the bowl is a snap with this one-piece design that eliminates the gap between the tank and the bowl. This toilet is sold with a seat, is available in five colors and has a five-year warranty.

If you are looking to spend less on a high-efficiency toilet, the two-piece Kohler Cimarron K-3609 (*Est. $260) has many of the same features as the Cimarron line discussed in the standard toilets section of this report. One professional review ranked it behind the American Standard Compact Cadet 3 FloWise in removal of solid waste, but it was on par in MaP testing. The consensus by a handful of owner reviews at HomeDepot.com is this water-efficient toilet has a "super flush." This toilet is also sold as The Complete Solution, which includes a seat and everything you need for installation. With seven color choices ranging from white to black, there's an option for any bathroom dŽcor. Kohler offers a one-year limited warranty on Cimarron toilets.

If you are willing to sacrifice some flush performance for a toilet that really does an excellent job at keeping the bowl clean, the Gerber Ultra Flush 1.1 EF-21-318 (*Est. $340) is a standout in one professional review. Although this pressure-assist toilet uses a mere 1.1 gpf, compressed air forces the water out to achieve only a slightly lower performance in MaP testing than the aforementioned 1.28 gpf gravity HETs. A pressure-assist toilet can surpass the performance of a gravity toilet in homes with older plumbing. It's important to note, however, that this toilet is noisier during flushing compared to the gravity models. This toilet is ADA-compliant like the American Standard Compact Cadet 3 FloWise, but it doesn't include a seat. Gerber backs this toilet with an impressive 10-year limited warranty on the china and vessel, and a five-year limited warranty on other parts.

Dual-flush toilets blend 1.6-gpf performance with a water-saving option

Dual-flush toilets are an option for consumers who want a toilet that meets EPA water conservation standards but uses more water to flush solid waste. Rather than a lever to flush, dual-flush toilets have two buttons: one uses 1.6 gallons of water to flush solid waste and the other uses 1.1 or 0.8 gallons to flush liquid waste. Like single-flush toilets, dual-flush toilets are usually gravity or pressure-assist; however, their double duty nature means they're often pricier. Because they are also less widely available online, we didn't find many owner opinions and had to rely mostly on expert reviews. The following three dual-flush toilets are two-piece and ADA-compliant.

The Gerber Ultra Dual Flush Elongated ErgoHeight DF-21-318 (*Est. $410) receives a top rating in one professional review for excellent results in removing solid waste and cleaning the bowl during flushing. This pressure-assist toilet uses compressed air and has a trap that's an inch wider than our Best Reviewed gravity toilets to achieve a powerful flush. In fact, it successfully removed 1,000 grams of solid waste in MaP testing. However, the water-saving, 1.1-gallon flush didn't completely remove all the blue dye in one liquid waste removal test. In 2007, engineers named the Gerber Ultra Dual Flush their product of the year in Consulting-Specifying Engineer magazine. This toilet is available in three colors (white, biscuit and bone), but the seat must be purchased separately. Gerber offers a 10-year limited warranty on the china and vessel, and a five-year limited warranty on other parts.

The Mansfield EcoQuantum 148-119 (*Est. $460) is another pressure-assist dual-flush toilet that receives high marks in professional reviews and successfully removed 1,000 grams of solid waste in MaP testing. This toilet is noisier and doesn't clean the bowl as well as the Gerber Ultra Dual-Flush in 1.6 gpf mode, but performs better in the liquid test in 1.1 gpf mode. If you want a color other than white, the biscuit or bone colors cost more. Mansfield offers a lifetime warranty on the china and a five-year limited warranty on the vessel.

The American Standard FloWise Dual Flush 2480.216 (*Est. $335) is a gravity dual-flush toilet that performs just as well as the Gerber and Mansfield in one professional review; however, only successfully removed 600 grams of solid waste in MaP testing. Because it only uses 0.8 gpf in high-efficiency mode, it's not as powerful or effective at bowl cleaning as the 1.1 gpf models. However, it's significantly quieter, costs less and includes a seat. The FloWise Dual Flush has a two-year warranty and is only available in white.