Leak & Water Waste Calculator — Gallons and Dollars
A faucet dripping once a second wastes 2,083 gallons a year and costs about $26. A toilet running silently in the next room wastes 73,000 and costs $913. The leak you can hear is almost never the expensive one — this prices the one you cannot.
Price the leak
One drip a second is 60 a minute. Past about 180 the drips merge — use the fill test instead.
A standard measuring cup is 8 fl oz. Catch the leak for a timed run and read the volume.
Every fixture and appliance off. Any movement at all is a leak somewhere on your side of the meter.
Straight from a flow meter, or a known fixture rate for something left running.
A cold supply leak is 0. A dripping shower or a hot-side valve is 100 — and you paid to heat every gallon of it.
Your rates — change these to your own bill
Rates vary enormously by utility. Sewer is normally billed on metered water in, not on what reaches the sewer — which is why a leak is usually charged twice.
Costing you every year
2,083 gallons a year, at 5.71 gallons a day.
Per day
5.71 gal
Per year
2,083 gal
You are paying for this water twice
See the breakdown
A planning figure, not a bill. Water, sewer and energy rates vary enormously by utility and many bills are tiered, so put your own numbers in above. Ask your utility whether it offers a leak adjustment once the repair is documented — many do.
The leak you can hear is not the expensive one
Every row priced at the default rates on this page. A faucet dripping once a second is $26 a year. A toilet running where nobody is listening is $4,563 — 175 times as much, for a fault that costs a few dollars in parts to fix.
| Leak | Per day | Per year | Cost |
|---|---|---|---|
| Faucet dripping once a second 60 drips a minute — audible, and the one people notice | 5.7 gal | 2,081 gal | $26 |
| Faucet dripping fast 180 drips a minute, close to a thread of water | 17.1 gal | 6,242 gal | $78 |
| Showerhead dripping 100 drips a minute, and it is all heated water | 9.5 gal | 3,468 gal | $79 |
| Toilet with a silent flapper leak No sound at all — found by dye in the tank | 200.0 gal | 73,000 gal | $913 |
| Toilet visibly running The single most expensive household leak | 1,000.0 gal | 365,000 gal | $4,563 |
| Irrigation head broken off Runs only during the zone's schedule, but at full flow | 1,500.0 gal | 547,500 gal | $6,844 |
| Underground service line seep Invisible — shows only on the meter or the bill | 300.0 gal | 109,500 gal | $1,369 |
Daily volumes are the ranges published in EPA WaterSense and utility conservation material — common starting points, not measurements. Measure the leak in front of you rather than looking it up.
Drips to gallons
One published constant does the whole conversion: the USGS figure of 15,140 drips per gallon. That reconciles exactly with a 0.25 mL drop — 3,785.41 mL in a gallon divided by 0.25 is 15,140.0, the same number by a different route.
| Drip rate | Per day | Per year | Cost, cold |
|---|---|---|---|
| 10 per min | 0.95 gal | 347 gal | $4 |
| 30 per min | 2.85 gal | 1,041 gal | $13 |
| 60 per min | 5.71 gal | 2,083 gal | $26 |
| 120 per min | 11.41 gal | 4,166 gal | $52 |
| 180 per min | 17.12 gal | 6,249 gal | $78 |
A hot leak is charged twice
Most leak calculators stop at the water bill. But a hot-water leak was heated before it escaped, and that energy is gone too. The same 5.71 gpd drip costs $26.04 a year on the cold side and $47.29 on the hot — 1.82× — with 15.2 therms going up the flue for nothing. On an electric resistance heater the energy share is worse still, at 71% of the total.
It is the reason a dripping shower head deserves more attention than a dripping outside tap, even though the tap is usually dripping faster.
Finding it
The meter test settles it. Shut every fixture and appliance, read the meter, wait thirty minutes to two hours, read it again. Any movement is a leak on your side. Most meters also carry a small triangular or star-shaped low-flow indicator that turns on flows far too small to register on the dial — if that is moving with the house shut down, water is going somewhere.
For toilets, use dye. A few drops of food colouring in the tank, fifteen minutes without flushing, then look in the bowl. Colour in the bowl is a flapper leak — the 200 gallon-a-day fault that makes no sound and costs $913 a year.
Scale it against the household figure. EPA WaterSense puts the average home at around 10,000 gallons a year lost to leaks, with about 10% of homes losing 90 gallons a day or more. A running toilet gets through that entire annual figure in 10.0 days. The dripping faucet takes 1,754 days — a little under five years.
Sources & standards: the drip conversion uses the USGS figure of 15,140 drips per gallon, and every other volume on this page is arithmetic from it. Household leak volumes and the 10,000 gallon household figure are EPA WaterSense estimates, quoted for scale rather than measured here. Water, sewer and energy rates are editable defaults, not published figures — bills are frequently tiered and vary enormously between utilities. The energy calculation heats the hot share of the wasted water through your temperature rise at your heater's efficiency. None of this is code; it is arithmetic on your own bill.
Frequently asked questions
Common questions about leak volumes, finding leaks, and what they actually cost.
How much water does a dripping faucet waste?
At one drip a second — 60 drips a minute — a faucet wastes 5.71 gallons a day, or 2,083 gallons a year. At the default rates on this page that is about $26 a year. It is the leak everyone notices and very nearly the cheapest one you can have.
Why does a running toilet cost so much more?
Because it is a continuous flow rather than a drip. A visibly running toilet passes roughly 1,000 gallons a day against the faucet's 5.7 — so it costs about $4,563 a year against $26, which is 175 times as much. The leak you can hear is almost never the expensive one.
What is a silent toilet leak and how do I find it?
A worn flapper letting tank water seep into the bowl with no sound at all. At around 200 gallons a day it costs roughly $913 a year and gives you nothing to hear or see. Find it by putting food colouring in the tank, waiting fifteen minutes without flushing, and checking whether colour has reached the bowl.
Does a hot water leak cost more than a cold one?
Yes, and by more than people expect — this is the part most leak calculators leave out. The same 5.71 gpd drip costs $26.04 a year on the cold side and $47.29 on the hot, because you paid to heat every gallon before losing it. That is 1.82× on gas; on an electric resistance heater the energy is 71% of the total.
How do I check my house for a leak?
Shut every fixture and appliance that uses water, then read the meter and read it again after thirty minutes to two hours. Any movement is a leak. Most meters also carry a small triangular or star-shaped low-flow indicator that spins on tiny flows — if it is turning with everything off, water is going somewhere. This is the only test that catches an underground service line leak.
How do I measure a leak I cannot count drips on?
Catch it. Hold a measuring jug or a marked container under the leak for a fixed time, then enter the volume and the seconds into the fill-test mode above. It is faster and far more accurate than counting drips once the leak is running faster than about three drips a second.
Am I charged sewer on water that leaks away?
At most utilities, yes. Sewer is usually billed on metered water in rather than on what actually reaches the sewer, so a leak is charged twice before any heating is counted — which is why sewer is a separate line here. Some utilities offer a one-time leak adjustment once the leak is repaired and documented; it is always worth asking.
How much water do household leaks waste in total?
EPA WaterSense puts the average household at around 10,000 gallons a year lost to leaks, with about 10% of homes leaking 90 gallons a day or more. At the default rates that 10,000 gallons is roughly $125 a year — and a running toilet gets through the whole annual figure in 10.0 days.
Where do the drip figures come from?
From one published constant: the USGS figure of 15,140 drips per gallon. Everything else on this page is arithmetic from it. That constant reconciles with a 0.25 mL drip — 3,785.41 mL per gallon divided by 0.25 mL gives 15,140.0, which is the same number.
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