How Much Is a Running Toilet Costing You?

A running toilet can cost you anywhere from a few dollars a month to more than $2,000, depending on how bad the leak is and what your city charges for water. The worst case is a stuck fill valve, which the Environmental Protection Agency says can waste 4,300 gallons a day. A worn flapper that lets water seep into the bowl wastes far less, but it does it around the clock, often without a sound.

In most homes you pay for every one of those gallons twice, once as water and again as sewer. The usual fix is a rubber part you can change yourself in a few minutes.

How much water a leak wastes

The EPA’s WaterSense program puts the average family’s household leaks at 180 gallons a week, or 9,400 gallons a year. That’s about 26 gallons a day, from every drip and seep in the home combined, and the same program says 9 percent of homes have leaks that waste 50 gallons or more a day.

One leaking toilet can waste far more than either of those figures.

An EPA leak checklist for building managers says a running toilet can waste 10 times what a dripping faucet does, and it puts the faucet at 3,000 gallons a month. That works out to 30,000 gallons a month for the toilet, or about 1,000 a day.

The agency’s February 2026 fact sheet on leak detection goes higher still, at 4,300 gallons a day for a toilet whose fill valve has stuck open.

A stuck fill valve wastes more water in one day than an average home’s leaks do in five months.

Turning gallons into dollars

To price a leak, you need your combined water and sewer rate per gallon, and New York City’s rates make the arithmetic easy to follow. For the year that started July 1, 2026, the city’s Water Board charges $5.35 per 100 cubic feet of water, plus a sewer charge of 159 percent of that, or $8.51.

Together that’s $13.86 per 100 cubic feet. One hundred cubic feet holds 748 gallons, so each gallon costs a little under 2 cents, or $18.53 per 1,000 gallons.

Leak, gallons a day	Cost a day	Gallons in 30 days	Cost in 30 days
26	$0.48	780	$14.45
50	$0.93	1,500	$27.79
1,000	$18.53	30,000	$555.88
4,300	$79.68	129,000	$2,390.29

Example: each leak priced at New York City’s combined water and sewer rate of $13.86 per 748 gallons.

At that rate, the average home’s 9,400 gallons of yearly leaks would cost $174.18.

New York isn’t cheap, so your number may well be lower. The EPA’s own estimate for a stuck fill valve is up to $1,400 a month, which assumes a lower rate than New York’s. To run your own numbers, find the water and sewer rates printed on your bill and add them together before you multiply.

Three costs on every leak

Three costs decide what a toilet leak takes from you, and the first two sit on your water bill. Your water charge is usually listed per 1,000 gallons or per unit, where a unit is often 100 cubic feet, shown as CCF.

The sewer charge is the one people forget. The EPA notes that many utilities have only one meter and bill both water and sewer on the water entering the house, so a toilet leak that goes straight down the drain gets billed both ways. In New York, sewer is the bigger of the two charges.

The third cost is the part. A flapper or a fill valve comes from any hardware store, and the EPA suggests bringing the old flapper, or a photo of it, so the new one fits your toilet.

Leak size, rates and toilet age

How big your leak is moves your number more than anything else. A flapper that seeps a little may waste a few gallons a day, while a fill valve that never shuts off can run up the thousands in the chart.

Your rate structure matters too. Many utilities charge more per gallon as your use climbs, a setup the EPA calls an increasing block rate, and on that kind of bill your leaked water lands in the most expensive tier. Check your bill for a rate table with more than one price per unit, and note which tier your monthly use reaches.

Your toilet’s age works against you in two ways. Rubber flappers wear out, and WaterSense says to check yours now and then and replace it at least every five years.

Older toilets also use more water on every normal flush. The Energy Policy Act of 1992 set a federal limit of 1.6 gallons per flush for new home toilets starting January 1, 1994. Before that, standard toilets usually took at least 3.5 gallons, and the EPA says some older models use as much as 6.

The 10-minute dye test

The EPA’s toilet test needs nothing more than the food coloring in your kitchen cupboard. Lift the tank lid and set it somewhere safe, since it’s heavy porcelain. Put a few drops of food coloring in the tank water, then leave the toilet alone for 10 minutes without flushing.

If color shows up in the bowl, water is getting past the flapper and you have a leak. Flush afterward so the dye doesn’t stain the bowl.

Ink and halftone illustration of a bright home bathroom. The woman in the dark headwrap and long olive cardigan leans over a toilet with its tank lid resting on a folded grey towel on the seat, squeezing dark drops of food coloring from a small dropper bottle into the tank water, where they swirl down toward the flapper. — *Toilets account for nearly 30 percent of the water an average home uses indoors, according to WaterSense.*

Reading the meter at the curb

The dye test checks one toilet at a time, but your water meter checks the whole house. The EPA says you’ll usually find it near the curb in front of your home, or inside, often in a basement, in cold climates. The lid is heavy, and a screwdriver helps you pry it up.

Pick a two-hour stretch when nobody will use water, note the reading, and look again when the time is up.

If the meter doesn’t read exactly the same, you probably have a leak somewhere.

Your bill can raise the alarm before you ever open the meter box. The EPA says a family of four probably has a serious leak if its winter water use tops 12,000 gallons, or 16 CCF, a month.

Flapper or fill valve?

With the tank lid off, you can usually tell which part is failing by watching the water level. If water keeps spilling into the top of the overflow tube, or the fill valve hisses long after a flush, the fill valve isn’t shutting off.

If the water sits below the top of the tube and dye still reaches the bowl, your flapper isn’t sealing.

A fill valve set too high keeps topping the tank past the overflow tube, so water runs down to the bowl all day.

Before you swap either part, close the shutoff valve on the wall behind the toilet and flush to empty the tank.

Skip the new toilet

A leak is a poor reason to buy a whole new toilet. If yours was made after 1994, it already meets the 1.6-gallon limit, and a new flapper or fill valve stops the leak for the price of the part. A WaterSense model at 1.28 gallons a flush would save you 0.32 gallons per flush, a small amount next to a leak of even 50 gallons a day.

A toilet from before 1994 is a different case. WaterSense says the average family can save nearly 13,000 gallons and more than $170 a year by replacing all of its old, inefficient toilets with labeled models. If your old toilet keeps needing parts, that saving is a fair reason to replace it.

Not sure how old yours is? Many tanks have a manufacture date stamped inside, often on the back wall or under the lid.

Leaks that need a plumber

You can swap a flapper or a fill valve yourself, but some toilet leaks need a pro. Water pooling around the base of the toilet usually means the seal between the toilet and the floor flange has failed, and fixing it means pulling the toilet off the floor.

A dripping supply line, a leaking shutoff valve or a cracked tank also belongs to a licensed plumber. The EPA’s own leak checklist points you to one for supply lines that fail.

If the toilets pass the dye test and your meter still moves, run the meter test one more time with the shutoff valve behind every toilet closed. A meter that moves at all over those two hours means the leak is somewhere past the toilets, and that’s the point to call a licensed plumber.