Best Options for High-Efficiency Toilets

With inexpensive new designs, you can flush less water and money down the drain.

| April/May 2010

Dan installing toilet illustration

With only a few simple tools, you can install a new water-efficient toilet.


With water shortages becoming more common, numerous states and nations are enacting regulations to conserve water. The efforts have centered primarily on water efficiency — ways to meet our needs using the least amount of water. One popular approach is the installation of high-efficiency toilets to replace old, water-intensive ones, which consume as much as 7 gallons per flush. If your home has an old toilet, it makes sense — economically and environmentally — to replace it with a water-conserving model that will use about 55 percent less water than a conventional toilet.

Installing a high-efficiency toilet can save you a substantial amount of money by reducing your water bills. Water-efficient toilets also reduce our collective pressure on limited water supplies and, in urban areas, the amount of waste flowing to sewage treatment plants. Less waste lowers the plants’ operating energy and costs.

In rural areas not served by municipal wastewater treatment plants, water-efficient toilets reduce the amount of waste flowing into septic tanks and leach fields, extending the lives of these systems. If you use well water, an efficient toilet will also cut down the run time of your well pump, reducing electrical consumption. Plus, the less your pump runs, the longer it will remain in service.

What Are Your Options?

Water-efficient toilets fit into three categories: single-flush at 1.6 gallons per flush (gpf), dual-flush toilets (1.6 gpf/0.8 gpf) and pressure-assist toilets (1 gpf). Single-flush toilets using 1.6 gallons per flush are now required by law in most new home construction and bathroom remodels. Although the earliest water-efficient toilets had some problems (such as tanks that were too small and lacked sufficient flushing power), most water-efficient toilets on the market today work well.

As the name implies, dual-flush toilets provide two flushing options. Solids are flushed with 1.6 gallons of water. Liquids are flushed by about half that volume — 0.8 to 0.9 gpf. Most manufacturers offer at least one dual-flush toilet.

The third option is a toilet equipped with pressure-assist technology, available from all leading manufacturers. Most common in hotels, restrooms and commercial buildings, these toilets also can be installed in homes. The pressure-assist system consists of a plastic pressure tank mounted inside the toilet tank. It uses pressure from the water supply line to compress air inside the pressure tank. This system traps and compresses air as it fills with water. The compressed air forces the water into the bowl when the toilet is flushed. The pressure-assist unit uses this force to push waste out, creating a vigorous flushing action that whisks away waste and cleans the bowl with only one gallon of water per flush.

3/2/2016 11:18:42 AM

You should look into the brand new technology out called BLACK MOLD ON HOLD. It includes a new sealed bottom, WATERTIGHT toilet flange (kid you not) that directs any leaking water right back down the drain. Amazing! It's made by Barracuda Brackets.

10/31/2015 2:12:11 PM

I bought American Standard 2034.014.020 Champion-4 Right Height One-Piece Elongated Toilet. After many researches I realized that ıt is the best and top rated toiletvin the market . In that time, it has proven to be exactly what I wanted — a good-looking, one-piece, solid toilet that never got clogged or needed plunging. It replaced a very high-end, more expensive Toto that looked even better than this one does, but did get clogged on occasion, and did act oddly sometimes when flushed (the Toto would sort of shoot back water upwards…very strange — only did it sometimes but, you know, one thing most people expect in a toilet is that the water and contents stay in it when it’s flushed!). The other consideration was to get another Kohler Cimarron which I also have in another bathroom. It is a very good-looking toilet too, and usually does it’s job well, but it does get clogged at times, so, after reading extensive reviews on many sites, I decided to go with the American Standard, and I am very glad I did. Not to be indelicate, but I had a bout of constipation about a month ago that lasted four days. When it finally released, I just had to know what this toilet could do. So I did not flush until the evacuation was over completely. It took two flushes, but it got it all and did not clog! you can check and get great and informational reviews.

6/23/2015 7:11:36 AM

I was in a Theatre in london and the toilet only used 0.329 gallons per flush and had no trouble clearing the pan

6/25/2010 1:15:09 PM

I have had water saving toilets in my house since 1986. They are/were one gallon flush. The ones from that era do not flush very well, but it was all they made at the time. My thought was, "so what if I have to flush twice for solids, I'm still using less water". As for the distance to the sewer line, mine is also about 200 feet. I have only had my line block twice, and I think it was more about what was flushed. A stuffed animal one time, and it got caught in the trap. I recently replaced one toilet with a dual flush, and was disapointed to find out it was rated at 1.6 gpf. I think I might try the pressurized one to replace my second toilet. I like the idea of it having more water in the bowl, and staying cleaner.

barbara gillihan
4/30/2010 12:47:40 PM

Jim, I am interested in your using urine on a compost pile. Dilluted "what to what"? Have you done this before? Would be a real saving on "burnings" of the incinerator toilet. Thanks

jim adams
4/30/2010 10:03:28 AM

The numbers your article give are most relevant for city folks who buy their water and flush after every use of the toilet. My wife and i live in the country, have a well, a low pressure water system, and we flush solids and occasionally liquids... usually before they begin to smell. We--together flush 11 to 12 gallons away every day in cold weather. In warmer weather, we distribute our nitrogen rich urine on various plants (especially trees) and this year we are considering peeing in a jar or bucket and pouring our urine on the compost pile or various places in the we flush 7-8 gallons with our old low flow, standard flush system. Whilst i generally like the lo-flow toilets i've used, i don't see much benefit from them for us. + I really like the assisted flush (thanks for explaining how they create pressure) but we only have 35-40 psi in our water line. What psi do the assisted flush toilets require? I know there is an electric assisted flush on some but we'd rather not go there. It seems to me that we use less water than most of the citified low-flo folks ... so while we thank you for the info (which we will pass on to our townie friends and others), I think we'll pass for now. thanks again, jim n'shana

barbara gillihan
4/30/2010 9:25:56 AM

I don't have experience in these toilets, but have had an Incinolet, incinerator toilet for 10 years. Waterless, it works fine for a family of 2 plus occasional company. I know you prob. wonder what happens if the electricity is out, but your well won't pump anyway. We make alternative plans. For people like us who live in the woods, have rock in the soil and just can't put in a septic system, this is a perfect alternative and it uses very little electricity, plugging into a regular wall socket.

topeka ev driver
4/30/2010 9:01:37 AM

Does anyone have any experience with these past the point of flushing? In my house the solids still have a 200 foot journey to the sewer line with a few of the ever present roots along the way. I don't believe 1.5 gallons can do that.

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