Leaky Faucet Water Waste Calculator: How Much Water and Money a Dripping Tap Wastes
Turn a leaky faucet’s drips per minute into gallons or litres wasted per day, month and year, and what it adds to your water bill.
How it works
Drips per day = faucets × drips per minute × 1,440 · Water per day (mL) = drips per day × drip volume (0.25 mL by default) · Per year = per day × 365 · 1 US gal = 3,785.41 mL, so 15,140 drips ≈ 1 gal and 4,000 drips = 1 L · Cost = gallons ÷ 1,000 × price per 1,000 gal (or m³ × price per m³)
Count how many times the faucet drips in a minute. Multiply by 1,440 minutes in a day and by the volume of one drip to get the water lost per day, then by 365 for a year. There is no official size for a drip; the US Geological Survey’s drip calculator uses a quarter of a millilitre (about 15,140 drips per US gallon, or 4,000 per litre), which is the default here. EPA’s WaterSense figures (more than 3,000 gallons a year at one drip per second, and more than 500 gallons a year for a showerhead dripping 10 times a minute) imply a larger drip of about 0.36 mL, so you can change the drip size under More options. Add your water price, including sewer if it is charged on metered water, to see the yearly cost, and a number of days to see what has already been lost. The table compares other drip rates, and the shower figure uses EPA’s comparison of 3,000 gallons to about 180 showers. The cost of a single drip is usually small, but it adds up across a house and a year, and a hot-water drip also wastes the energy used to heat it. Unlike a household water-use or water-bill calculator, this one starts from a drip count.
Worked example
One faucet dripping 10 times a minute drips 1 × 10 × 1,440 = 14,400 times a day. At 0.25 mL per drip that is 3,600 mL = 3.60 L or 0.951 gal a day, and 0.951 × 365 = 347 gal (1,314 L) a year, about 29 gal a month. At $12 per 1,000 gallons it costs 347 ÷ 1,000 × $12 = $4.17 a year, and the water would cover about 21 showers.
Sources: USGS Water Science School: Drip calculator (0.25 mL per drip, 15,140 drips per gallon) · US EPA WaterSense: Fix a Leak Week (one drip per second wastes more than 3,000 gallons a year) · Omni Calculator: Drip faucet calculator (1/4 mL per drip)
Frequently asked questions
How much water does a dripping faucet waste?
At 10 drips a minute and a quarter-millilitre per drip, about 3.6 litres (0.95 gallon) a day, or 347 gallons (1,314 litres) a year. At one drip per second it is about 2,080 gallons a year with USGS’s drip size, or more than 3,000 gallons with EPA’s larger estimate.
How many drips are in a gallon?
About 15,140, if each drip is a quarter-millilitre, as the US Geological Survey assumes. That is 4,000 drips per litre. Larger, slower drips mean fewer drips per gallon.
How much does a leaky faucet add to the water bill?
Usually a few dollars a year for one slow drip, but a fast drip or several leaks can cost $20–$50 or more, especially where sewer is charged on water use. Enter your rate from the bill to see your figure.
How do I measure my faucet’s drip rate?
Watch it with a timer for 60 seconds and count the drops, or count for 15 seconds and multiply by 4. To measure drip size, catch the drips in a measuring cup or a kitchen measuring jug for 10 minutes and divide the volume by the number of drips.
Why does a faucet keep dripping?
Most drips come from a worn washer, O-ring or seat in compression faucets, or a worn cartridge in single-handle faucets. Replacing the part usually costs little and stops the waste.
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This calculator is for educational purposes. Double-check important results before acting on them.