How to Save Water With Your Toilet

Saving water with your toilet comes down to two separate jobs that people often blur together. The first job is to stop wasting the water you already have, which means finding and fixing silent leaks, setting the tank fill to the correct line, and using the right flush for the job. The second job is to draw less water on every flush, which means moving from a thirsty older toilet to a modern low-flow or dual-flush model that uses 1.28 gallons or less while still clearing the bowl in one push. Do both and a typical four-person household can cut thousands of gallons a year off its water bill, with no change in how the bathroom actually feels to use.

We do not run our own flush trials. Instead we compare published manufacturer specifications, independent MaP (Maximum Performance) flush-test gram scores, EPA WaterSense certification, the rated gallons per flush, the flush-system and flush-valve design, and the patterns across thousands of verified owner reviews. For saving water specifically, two numbers matter above all others and have to be read together: the gallons per flush, because that is the savings, and the MaP gram score, because a low-water toilet only saves water if it clears the bowl in one flush instead of two. A weak low-flow toilet that needs a double flush uses more water than the old model it replaced. If you want the broadest performance-first ranking across every toilet type, start with our pillar guide to the best flushing toilets.

How much water does a toilet actually use?

To know how much water you can save, it helps to know where the standards sit. Before 1992 there was no federal limit, and toilets commonly used 3.5 gallons per flush, with some older models using 5 to 7 gallons. The Energy Policy Act of 1992 capped new toilets at 1.6 gallons per flush starting in 1994, which is still the legal maximum today. The EPA's voluntary WaterSense program goes further, certifying toilets that use 1.28 gallons or less while still passing independent flush-performance tests. Dual-flush toilets drop the light flush to roughly 0.8 to 1.1 gallons, which pulls the daily household average even lower because most flushes are liquid only.

Recommended toilets in this guide

TOTO Drake II

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TOTO Aquia IV

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Kohler Cimarron

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The arithmetic is striking. If one person flushes six times a day, an old 3.5 gallon toilet draws about 21 gallons daily, while a 1.28 gallon WaterSense toilet draws about 7.7 gallons, a difference of more than 13 gallons per person per day. For a household of four, that is more than 19,000 gallons saved in a year from a single fixture change. Even moving from the 1.6 gallon standard to a 1.28 gallon WaterSense toilet saves about 0.32 gallons per flush, which still adds up to several thousand gallons a year for a busy household.

What is the fastest way to save water with your toilet?

The single most overlooked source of toilet water waste is the silent leak. When the rubber flapper or the canister flush-valve seal wears out, water seeps from the tank into the bowl continuously, and because it makes little or no sound you may never notice it. A bad leak can waste anywhere from a few gallons to hundreds of gallons a day, which means a leaking 1.28 gallon toilet can quietly use more water than a working 3.5 gallon model. The food-coloring test takes two minutes and the replacement flapper costs only a few dollars, making this the highest-return water fix you can perform.

After leaks, the next free win is the tank fill level. Many fill valves are set higher than necessary, sending water straight over the overflow tube on every refill. Lower the float so the water line sits about one inch below the top of the overflow tube, which trims a small amount from every single flush at no cost. Avoid the old trick of dropping a brick in the tank, since bricks crumble and can damage the flush valve. If you want to displace water, use a sealed plastic bottle filled with water and gravel, placed away from the moving parts.

Should you replace your toilet or just fix it to save water?

The right path depends on how old your toilet is. If your toilet was installed before 1994, it almost certainly uses 3.5 gallons per flush or more, and no flapper swap or fill adjustment can change the bowl and trap design that were built around that much water. For these toilets, replacement with a WaterSense model is the single largest water saving available in the bathroom, and many water utilities offer rebates that offset much of the cost. Check the date stamp molded inside the tank lid or behind the seat to estimate the age.

If you already have a 1.6 gallon toilet, the calculus shifts. A new 1.28 gallon WaterSense toilet saves only about 0.32 gallons per flush, so the payback period on replacement alone is long. In that case the smarter sequence is to fix any leak, adjust the fill level, and switch to the partial flush on a dual-flush model before buying a new fixture. The exception is if your current 1.6 gallon toilet flushes weakly and forces double flushing, because then you are already using 3.2 gallons on those flushes and a strong 1.28 gallon model with a high MaP score will both save water and end the second flush.

What GPF and MaP score should you look for to save water?

This is the heart of saving water with a new toilet, and it is where most buyers go wrong. It is tempting to chase the lowest possible gallons per flush, but a low GPF number is meaningless if the toilet cannot clear the bowl in one push. The MaP test, run by the independent Maximum Performance program, measures how many grams of solid waste a toilet removes in a single flush, on a scale up to 1000 grams. A toilet that posts 1000 grams at 1.28 gallons, like the TOTO Drake II, clears any realistic household load on the first try, so the water savings are real and permanent.

Read the two numbers as a pair. The savings live in the GPF, but they are only guaranteed by the MaP score. A 1.28 gallon toilet that scores 350 grams will frequently need a second flush, which means 2.56 gallons used, more than a single 1.6 gallon flush. The toilets that genuinely save water pair a 1.28 gallon or lower rating with a MaP score of 800 grams or higher, and the safest choice is the 1000 gram ceiling. For the deepest dive on the efficiency numbers, see our breakdown of the best low flow toilets at 1.28 GPF and under.

Do water saving toilets really flush as well as older ones?

The myth that low-water means weak-flush is a holdover from the first generation of 1.6 gallon toilets in the mid-1990s. When the federal limit dropped from 3.5 to 1.6 gallons overnight, many manufacturers simply put less water in the same old bowls, which produced toilets that genuinely clogged and forced double flushing. That early failure scarred the category's reputation, but the engineering caught up years ago. Today's leaders move the same waste with far less water by redesigning the bowl and trap rather than just shrinking the tank.

The key advances are wider flush valves, which dump the tank into the bowl faster for a stronger siphon, and computer-modeled bowl and trapway shapes that use the water's momentum more efficiently. TOTO's Double Cyclone and Tornado systems, for example, send water through angled nozzles instead of a ring of small rim holes, creating a centrifugal scrub that clears the bowl with 1.28 gallons. Glazed trapways like TOTO's CeFiONtect and the glazed traps on Kohler and American Standard models let waste slide through without sticking. The result is that the strongest flushers on the market today are also among the most water-efficient.

If you decide a new fixture is the right move, these three cover the most common water-saving goals: the best all-around single-flush saver, the lowest daily average from a dual flush, and the best value. All three are EPA WaterSense certified at 1.28 gallons or less.

How a dual-flush toilet saves the most water

A dual-flush toilet gives you two buttons: a small partial flush for liquids, using roughly 0.8 to 1.1 gallons, and a full flush for solids, using 1.28 to 1.6 gallons. The savings come from the math of a normal day. In most households, liquid-only uses outnumber solid uses by a wide margin, so if the small button does most of the work the daily average can fall well below even an efficient single-flush 1.28 gallon toilet. The TOTO Aquia IV and Swiss Madison St. Tropez both reach a 0.8 gallon light flush, among the lowest available.

The catch, and it is a real one, is that the savings depend entirely on behavior. A dual-flush toilet only saves more water if everyone in the house actually uses the small button for liquids, which can be a hard habit to teach guests and children. If half the household defaults to the full flush every time, a dual-flush toilet ends up using about the same water as a good single-flush model while costing more to buy. Choose dual flush when you genuinely will use the partial setting, and choose a strong single-flush model when you want guaranteed savings with no behavior change required.

Habits that stretch every gallon further

Beyond the hardware, a few simple habits compound your savings. Never use the toilet as a wastebasket, since flushing a tissue or cotton ball wastes a full flush of water on something the trash can handle for free. Keep an eye and ear on the tank for the trickle of a developing leak, and replace the flapper at the first sign rather than waiting. On a dual-flush toilet, make the small button the default. And if you are setting up a new bathroom from scratch, pair the efficient toilet with WaterSense faucets and showerheads so the whole room runs lean. For more on the certification that ties this together, see our guide to the best EPA WaterSense certified toilets.

Toilet water-saving options compared

The table below summarizes the main ways to cut toilet water use, from no-cost fixes to a full replacement, so you can match the effort to your situation.

Which water saving approach is right for you?

Choose the fix-first path if your toilet is from 1994 or later and already rated at 1.6 gallons. Run the food-coloring test, replace the flapper if it leaks, lower the fill level, and use the partial flush if you have one. These steps cost almost nothing and capture most of the easy savings without a new fixture.

Choose the replacement path if your toilet predates 1994, uses 3.5 gallons or more, or flushes so weakly that you regularly flush twice. In all three cases the old toilet is the problem, and a strong 1.28 gallon WaterSense model with a 1000 gram MaP score both cuts the per-flush draw and ends the double flushing. Many water utilities offer rebates that make the swap even more attractive.

Why MaP score protects your water savings

It is worth restating the core principle because it is the one most buyers miss. Every double flush at 1.28 gallons uses 2.56 gallons, which is more than a single 1.6 gallon flush and far more than the savings you were chasing. The MaP gram score is what makes the savings real: a toilet that clears the bowl in one push at 1.28 gallons saves water on every use, for the life of the fixture.

The toilets that hit the 1000 gram MaP ceiling at 1.28 gallons, including the TOTO Drake, Drake II and UltraMax II, the Kohler Cimarron, and the American Standard Cadet 3, are the ones whose savings you can count on. Brands like Woodbridge, Swiss Madison and Gerber also field WaterSense models. Whichever brand you choose, confirm the WaterSense 1.28 gallon rating and a MaP score of 800 grams or higher, and your water savings are locked in. For a side-by-side on the two common ratings, see our comparison of 1.28 GPF vs 1.6 GPF toilets and which to choose.