The short answer
As much as 6 gallons every flush, if it’s old enough. The EPA says older toilets can use up to 6 gallons per flush. A new toilet is capped at 1.6 gallons, and the ones with the EPA’s WaterSense label use 1.28 or less. Plenty of Northern Virginia houses built before the 1990s still have at least one of the old ones.
Then vs now
Swipe to see all columns →
Swipe to see all columns →
| Toilet | Gallons per flush |
|---|---|
| Older toilets | Up to 6 |
| Federal limit for new toilets since 1994 | 1.6 |
| WaterSense labeled | 1.28 or less |
Swap a 6 gallon toilet for a 1.28 model and every flush uses about a fifth of the water. The toilet is the one fixture in the house that uses the most water: in the Water Research Foundation study of how homes use water, toilet flushing was the largest indoor use in single-family homes, even as indoor use per household fell 22% since 1999, from 177 gallons a day to 138.
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The part most people don’t know
The flush isn’t the worst of it. A toilet that leaks between flushes can waste more water than the flushing does, and it does it quietly. New York City’s water department says a toilet with its fill valve stuck open can waste up to 4,000 gallons a day. Most leaks are much smaller: a worn flapper that lets the tank trickle into the bowl, so the toilet refills by itself every so often.
Small leaks add up across a whole house. The EPA says the average household’s leaks can waste more than 9,300 gallons a year, and about 9% of homes have leaks that waste 50 gallons or more a day. Its rule of thumb: if a family of four uses more than 12,000 gallons in a winter month, there’s a serious leak somewhere.
The 10 minute dye test
- Take the lid off the tank and add a few drops of food coloring.
- Don’t flush. Wait 10 minutes.
- Color in the bowl means the flapper is leaking.
- Flush when you’re done so the dye doesn’t stain.
Water spilling into the overflow tube is the other common one: the fill valve or the water level is set too high. Our running toilet guide walks through both fixes, and what a running toilet does to the water bill puts a number on waiting.
Why so many old toilets are still around
Toilets last a long time. The porcelain doesn’t wear out; the parts inside the tank do, and those are cheap to swap. So a toilet made before 1994 can still be flushing today, using several times what the law now allows. Look for a stamp on the porcelain behind the seat or inside the tank: 1.6 GPF or 1.28 GPF. No stamp on an old toilet usually means more.
Fix it or replace it?
A running toilet is usually a flapper or a fill valve, a small repair. A toilet that’s cracked, rocks on the floor, or was made before 1994 is worth replacing, and the water it stops using helps pay for it over time. Our toilet replacement cost guide has the numbers, and why is my water bill so high covers the other leaks worth checking.
Have a plumber look
Our plumbers handle toilet repair and replacement across Northern Virginia. If you want the whole house looked at in one visit, the water heater flush is $99: we drain and flush the tank, check the anode rod and test the relief valve, then go through the house’s plumbing with photos, included.
Book it
Book the water heater flush, call (703) 997-9757, or book online from goswiftpro.com/cookiesoffer and a box of warm cookies comes with the visit. Rated 5.0 stars across 1,138 reviews on Google, Angi, Yelp, the BBB and Facebook, Virginia Class A license 2705192276.
Questions people ask
How many gallons per flush does an old toilet use?
The EPA says older toilets can use as much as 6 gallons per flush. New toilets are capped at 1.6 gallons, and WaterSense labeled toilets use 1.28 or less.
How do I tell how many gallons my toilet uses?
Look for a stamp on the porcelain behind the seat or inside the tank, like 1.6 GPF or 1.28 GPF. An older toilet with no stamp usually uses more.
How much water does a leaking toilet waste?
Anywhere from a trickle to a lot. New York City’s water department says a toilet with a stuck fill valve can waste up to 4,000 gallons a day. A food coloring test in the tank shows a leaking flapper in 10 minutes.
How do I know if my house has a leak?
The EPA’s rule of thumb: if a family of four uses more than 12,000 gallons in a winter month, there’s a serious leak somewhere. Check the toilets first.
Is it worth replacing an old toilet?
If it was made before 1994, is cracked or rocks on the floor, usually yes. A running toilet with a good bowl usually just needs a flapper or a fill valve.
