Leaky Faucet Drip Calculator

Where the 3,000 gallon number comes from

The number most people have heard is the one the Environmental Protection Agency uses during Fix a Leak Week: a faucet dripping one time per second wastes more than 3,000 gallons a year, which the agency says is enough water for more than 180 showers. That single sentence is the anchor for everything on this page, and it is worth slowing down on, because it tells you how much water a tiny drip carries.

One drip per second is 60 drips a minute. Run that for a full day and you get 60 x 1,440 = 86,400 drips. Set 86,400 against the 3,000 gallons the EPA quotes and you land at 10,500 drips to the gallon, which is the conversion this calculator uses. Divide it back out and 86,400 / 10,500 = 8.23 gallons a day, which is 3,003 gallons over a year. That is the same 3,000 gallons the agency publishes, reached from the other direction.

Real drips are not all the same size. Water pressure, the width of the opening and the age of the washer all change how much water sits in each drop, so treat 10,500 drips per gallon as a good national average rather than a physical constant. The pattern is what matters: the waste scales in a straight line with the drip rate, so twice as many drips per minute means twice as much water down the drain. Read more about the agency's own leak work on its Fix a Leak Week page.

How the calculator turns drips into gallons and dollars

There are only four steps between a dripping tap and a number on your bill, and you can do all of them by hand if you want to check the result.

• Drips per day. Drips per minute x 1,440 minutes in a day.
• Gallons per day. Drips per day / 10,500 drips per gallon.
• Gallons per year. Gallons per day x 365 days.
• Dollars per year. Gallons per year / 1,000 x your price per 1,000 gallons.

Take a slow tap that drips ten times a minute. Step one is 10 x 1,440 = 14,400 drips a day. Step two is 14,400 / 10,500 = 1.37 gallons a day. Step three is 1.37 x 365 = 501 gallons a year. Step four uses the national average price of water and sewer together, which WaterSense put at $16.83 per 1,000 gallons for a residential customer in 2024, so 501 / 1,000 x $16.83 = $8.42 a year.

Eight dollars is not going to change anyone's life, and it would be dishonest to pretend otherwise. The reason to fix the tap is that 501 gallons is real water you already paid to treat and deliver, and a leak that small is the easiest kind of leak to stop. The number also scales up fast: a tap dripping 60 times a minute, which is one drip per second, is 3,003 gallons a year and $50.55 on the same price. A thin, steady stream rather than separate drips can be several times that again.

What common drip rates cost over a year

The table below uses the 10,500 drips per gallon conversion and the WaterSense national average of $16.83 per 1,000 gallons for water and sewer combined. The last column adds the cost of heating the water, assuming an electric tank at 2.6 cents a gallon, for the case where the drip is on the hot side.

Read down the gallons column and the shape of the problem shows up: doubling the drip rate doubles the water. Most drips people live with sit somewhere between 5 and 30 a minute, which is 250 to 1,502 gallons a year, or somewhere between a long shower and a small backyard pool over the course of a decade.

A hot water drip costs you twice

When the leaking tap is on the hot side, the water bill is only half of what you lose. You also paid to heat that water, and then let it sit in the tank losing heat to the room. Heating water is not free, and the cost shows up on a different bill, which is why most people never connect it to the drip.

The physics is simple. A gallon of water weighs 8.34 pounds, and lifting the temperature from a cold 58 degrees to a hot 120 degrees is a 62 degree rise, so 8.34 x 62 = 517 BTU for every gallon. An electric tank turns that into 517 / 3,412 = 0.15 kWh. A gas tank loses some heat up the flue, so it burns roughly 517 / 0.78 = 663 BTU, which is 0.0066 therm. At ordinary U.S. residential energy prices that lands near 2.6 cents a gallon for an electric tank and about 1 cent a gallon for gas.

Put the two together for a 10 drip tap on the hot side with an electric tank: $8.42 for the water plus $13.01 to heat it, which is $21.44 a year. Heat pump tanks cut the heating part by roughly two thirds, so the same leak on a hybrid tank costs about $12.93 a year. Energy Saver guidance from the Department of Energy has more on how much of a home's energy budget goes to hot water.

The other leaks that beat a dripping faucet

A dripping tap is the leak you can hear, which is why it gets all the attention. WaterSense says the average household's leaks add up to more than 9,300 gallons wasted every year, and nine percent of homes have leaks running at 50 gallons or more per day. Put a price on the household figure and 9,300 / 1,000 x $16.83 = $156.52 a year, which is more than most people spend on the leak they can hear.

Toilets are usually the bigger offender. A flapper that has gone soft lets water slide from the tank into the bowl all day without a sound, and the only clue may be a toilet that refills itself every few minutes for no reason. Showerheads that dribble after you shut the valve, and the supply line under a sink that has started to sweat, are the other two worth checking. The fix for a faucet is usually a washer or a cartridge that costs a few dollars, while a flapper costs about the same and takes five minutes to swap.

WaterSense also notes that the average family spends more than $1,000 a year on water costs and can save more than $380 a year by moving to WaterSense labeled fixtures and ENERGY STAR certified appliances. The drip is the small end of that range, but it is also the end you can fix tonight with a screwdriver.

How to count your own drips in a minute

You do not need to sit and watch a faucet for a full minute. Pick a window that matches the speed of the drip and scale it up.

• Slow drip. Count for 15 seconds and multiply by 4, since 15 x 4 = 60 seconds. If you count 3 drips, you have 12 drips a minute.
• Medium drip. Count for 30 seconds and multiply by 2.
• Fast drip or a thin stream. Put a measuring cup under it and time how long it takes to collect a quarter cup. Two tablespoons is about a fluid ounce, so a cup every 15 minutes is a real leak even if you cannot count the drops.
• More than one tap. Count each one and add them, or take the worst one and run the number for the whole house with the faucet count field set to how many are dripping.

Do the count with the tap in the position it sits in most of the day. A single handle mixer left in the middle often drips on the hot side, which quietly mixes in the heating cost from the section above.

What fixing it usually involves

Most dripping faucets come down to one worn part. Compression faucets, the kind with two separate handles, usually need a new rubber washer at the end of the stem, and older ones also need the O ring around the stem replaced. Ceramic disc and cartridge faucets need a new cartridge, which is a single part you pull out of the body of the tap.

Shut the water off at the angle stop under the sink first, and put the drain plug in before you start, because small screws have a way of going straight down the drain. Take the old part with you to the hardware store and match it. Whole washers and O rings cost a couple of dollars; a replacement cartridge runs more but is still a small purchase, and both are far cheaper than a service call. If you rent, report the drip to the landlord in writing, since in many states the owner is responsible for keeping the plumbing in working order.

One honest note about the economics: the water saved will not pay for a plumber on its own. A 10 drip tap saving $8.42 a year would take many years to cover a few hundred dollars of labor. Fix it yourself because it is easy, and because a tap left dripping for years can stain the sink, and a supply line left sweating can do real damage to the cabinet below.

Where these numbers come from and what they leave out

Every figure on this page traces to a published source, and none of them are exact for your house. Here is the list, so you can check the ones that matter to you.

The calculator does not know your utility's rate structure. Many utilities charge more per gallon as you use more, and almost all of them bill a fixed monthly charge no matter what you use, so the money you save on the bill can be higher or lower than the figure here. Drought surcharges and summer rates push it higher. See the WaterSense data page for how the national price is built, and your own bill for what you pay.

This is a planning estimate, not a bill. Utility rates, water pressure and drop size all vary, so use the number to decide whether a repair is worth doing, not to predict a refund.