If you're in the market for a new toilet, experts say flush performance and water consumption (the amount of water used during a flush) are the most important considerations, aside from aesthetic considerations. If you're replacing a toilet from the 1980s, any modern toilet will result in a huge water savings; that's because toilets manufactured before 1994 used more than 3 gallons of water with every flush. These days, most toilets use 1.6 gallons of water per flush (gpf), and other more water-efficient models use 1.28 gpf or less. Dual-flush toilets, a hybrid alternative, feature one button to provide an effective 1.6-gallon flush for solids and a second button which typically uses a mere gallon of water to flush liquids. On the downside, it's important to note that some water-efficient toilets have been shown to have weaker flushing power, which can be an issue for consumers with problematic plumbing.
Indeed, whether a toilet can do its job in a single flush is an important factor. Overall, we found The Maximum Performance (MaP) Testing of Popular Toilet Models (15th Edition) to be an excellent resource for determining which toilets are the most effective and powerful. This review performs objective testing on more than 1,200 toilets using a paste made of soybean and rice to simulate human waste. Each toilet must pass at least four out of five separate flushing tests using the soybean paste and wads of toilet paper. The minimum standard is 250 grams of solid waste (an average solid-waste standard for an adult), and toilets are tested up to 1,000 grams.
Flush power and water usage aside, there are currently several types of toilets on the market today. Gravity toilets, which have been around the longest, open a simple valve in the bottom of the tank during a flush that drops water down into the bowl. Pressure-assist toilets, on the other hand, hold the water in the tank under air pressure, which dispels the water with greater force and noise during a flush. Vacuum-assist and power-assist toilets are two other options that feature quieter flushes. However, vacuum-assist units tend to be less powerful than the other units above and power-assist toilets, which require an electrical outlet, can be much more expensive.
Aside from the excellent MaP study, ConsumerReports.org is a solid review resource. Editors there test 19 single-flush toilets and six dual-flush toilets for their ability to remove simulated waste, and clean the inside of the bowl during flushing. Each model's seat is also removed during the flush to more accurately evaluate their noise level. Although this review includes a large number of toilets, we were disappointed to see that some of the models from the same manufacturer were quite similar. Other reviewers have also criticized ConsumerReports.org solid waste test, which uses plastic balls, latex cylinders and sponges weighted with screws, saying it doesn't accurately mimic human waste.
Several plumbers also maintain blogs with useful toilet reviews, but these are more limited in scope. For example, Terry Love, an experienced plumber in Bellevue, Wash., evaluates water-efficient toilets based on MaP testing, quality control at the factory, ease and cost of repairs, how they sound when flushing, how well the bowl is rinsed and perception of quality. WetHeadMedia.com and 411Plumb.com are other toilet review sites created by plumbers. We found these sites to be helpful when compared to professional tests and user ratings.
We found the most owner-written reviews at HomeDepot.com, HomeClick.com and ToiletsThatWork.com. Unfortunately, these sites tend to carry a limited number of brands. For example, Home Depot mainly sells Kohler and American toilets, while HomeClick.com specializes in Toto brand toilets. We also found some helpful owner reviews at Lowes.com, Amazon.com, EcoHuddle.com and AceHardware.com.
Before the 1950s, toilets used approximately 7 gallons of water per flush (gpf); by the 1980s, most toilets used about 3 gallons. In 1994, the National Energy Policy Act went into effect, mandating a water usage rate of 1.6 gpf. Manufacturers, in an attempt to produce toilets compliant with the new legal standards, tweaked the valves and floats in the tanks of toilets to reduce their water usage. Unfortunately, manufacturers didn't make significant changes to tanks or bowls, so two or more flushes were often needed in order to get the bowl to empty completely. All of this increased flushing cancelled out the primary intention of many low-flow toilets -- water conservation.
By now, that's all changed. According to HGTV.com, the Japanese manufacturer Toto has captured approximately one-third of the U.S. toilet market due to its innovative design changes. To improve its siphoning power, Toto decided to widen its flapper valve (or flush valve), which opens to allow water to flow from the tank to the bowl, from 2 inches to 3 inches. The trapway, which carries the waste down to the floor drain, was also redesigned with minimal curves. Other manufacturers, seeing their success, followed suit with similar design changes. Some products also now feature a glaze applied to the inside of the trapway to reduce friction and clogging.
Fast forward to today and high efficiency toilets (HETs) that use 1.28 gallons or less are becoming more commonplace. Since 2007, toilets earning the U.S. Environmental Protection Agency's (EPA) WaterSense label must have a maximum flush volume of 1.28 gallons and the ability to remove a minimum of 350 grams of solid waste per flush. According to the EPA, WaterSense toilets save 4,000 gallons of water per person annually. Dual-flush toilets, which let users choose between a 1-gallon (or less) flush for liquid waste and a 1.6-gallon flush for solids, are also now gaining in popularity in the U.S.