Faucet Leak Water Waste Calculator
One tap dripping once a second (60 drips/min) wastes 5.71 gallons a day and 2,083 gallons a year. At $10.00 per 1,000 gallons, that leak costs $20.83 a year.
Last reviewed
Water waste and annual utility cost
Water wasted per year
2,083 gal
Water & sewer cost per year
$20.83
At 60 drips/min per tap and 15,140 drips/gal across 1 faucet, you lose 5.71 gallons (21.60 L) a day.
That comes to 173.6 gallons a month and 2,083 gallons (7,885 L) over a 365-day year.
At $10.00 per 1,000 gallons, the leak adds $1.74 a month and $20.83 a year to your bill.
Over 5 years, waste hits 10,414.80 gallons ($104.15), and 1 year equals 25.4 person-days of home use (82 gal/day).
Leak rate, fixtures, and utility billing
- Daily drips = 60 × 1,440 × 1 = 86,400 drips/day
- Daily waste = 86,400 ÷ 15,140 = 5.71 gal/day (21.60 L/day)
- Annual waste = 5.7067 gal/day × 365 = 2,083 gal/year (173.6 gal/month)
- Annual cost = (2,082.96 ÷ 1,000) × $10.00 = $20.83
Cumulative gallons and liters wasted over time
Annual water waste against USGS and EPA benchmarks
Water waste and cost across drip rates
From 5 drips/min to 180 drips/min per faucet, annual waste scales from 174 gal ($1.74) to 6,249 gal ($62.49).
| Drip rate | Daily waste | Annual waste | Annual cost |
|---|---|---|---|
| 5 drips/min | 0.48 gal | 174 gal | $1.74 |
| 10 drips/min | 0.95 gal | 347 gal | $3.47 |
| 20 drips/min | 1.9 gal | 694 gal | $6.94 |
| 30 drips/min | 2.85 gal | 1,041 gal | $10.41 |
| 60 drips/min (closest to your input) | 5.71 gal | 2,083 gal | $20.83 |
| 90 drips/min | 8.56 gal | 3,124 gal | $31.24 |
| 120 drips/min | 11.41 gal | 4,166 gal | $41.66 |
| 180 drips/min | 17.12 gal | 6,249 gal | $62.49 |
Annual water wasted (gal) across drip rates for 1, 2, and 3 leaking faucets.
| Drips per minute (per faucet) by leaking faucets | 1 | 2 | 3 |
|---|---|---|---|
| 5 drips/min | 174 gal | 347 gal | 521 gal |
| 10 drips/min | 347 gal | 694 gal | 1,041 gal |
| 20 drips/min | 694 gal | 1,389 gal | 2,083 gal |
| 30 drips/min | 1,041 gal | 2,083 gal | 3,124 gal |
| 60 drips/min (closest to your input) | 2,083 gal | 4,166 gal | 6,249 gal |
| 90 drips/min | 3,124 gal | 6,249 gal | 9,373 gal |
| 120 drips/min | 4,166 gal | 8,332 gal | 12,498 gal |
| 180 drips/min | 6,249 gal | 12,498 gal | 18,747 gal |
Monthly and annual cost across water and sewer rates
From $5.00/kgal to $25.00/kgal, annual leak cost scales from $10.41 to $52.07.
| Rate per kgal | Monthly cost | Annual cost |
|---|---|---|
| $5 | $0.87 | $10.41 |
| $8 | $1.39 | $16.66 |
| $10 (closest to your input) | $1.74 | $20.83 |
| $12 | $2.08 | $25.00 |
| $15 | $2.60 | $31.24 |
| $20 | $3.47 | $41.66 |
| $25 | $4.34 | $52.07 |
Annual water and sewer cost across kgal utility rates for 1, 2, and 3 leaking faucets.
| Combined water + sewer rate by leaking faucets | 1 | 2 | 3 |
|---|---|---|---|
| $5 | $10.41 | $20.83 | $31.24 |
| $8 | $16.66 | $33.33 | $49.99 |
| $10 (closest to your input) | $20.83 | $41.66 | $62.49 |
| $12 | $25.00 | $49.99 | $74.99 |
| $15 | $31.24 | $62.49 | $93.73 |
| $20 | $41.66 | $83.32 | $124.98 |
| $25 | $52.07 | $104.15 | $156.22 |
Cumulative water waste and cost by time horizon
| Period | Water wasted (gal) | Water wasted (L) | Billing units | Water & sewer cost |
|---|---|---|---|---|
| 1 day (24 hours) | 5.71 | 21.6 | 0.01 | $0.06 |
| 1 week (7 days) | 39.95 | 151.22 | 0.04 | $0.40 |
| 1 month (1/12 year) | 173.58 | 657.07 | 0.17 | $1.74 |
| 3 months (1/4 year) | 520.74 | 1,971.21 | 0.52 | $5.21 |
| 6 months (1/2 year) | 1,041.48 | 3,942.43 | 1.04 | $10.41 |
| 1 year (365 days) | 2,082.96 | 7,884.86 | 2.08 | $20.83 |
| 5 years (1,825 days) | 10,414.8 | 39,424.29 | 10.41 | $104.15 |
Waste grows from 5.71 gallons ($0.06) on day 1 to 10,414.80 gallons (10.41 kgal, or $104.15) over 5 years.
Annual waste and cost across drop-size standards and leak benchmarks
| Benchmark or leak level | Total flow (mL/min) | Daily waste (gal) | Annual waste (gal) | Annual waste (L) | Annual cost |
|---|---|---|---|---|---|
| Your current setting | 15 | 5.71 | 2,083 | 7,885 | $20.83 |
| Slow drip: 10 drips/min × your taps (USGS 15,140 drips/gal) | 2.5 | 0.95 | 347 | 1,314 | $3.47 |
| 10 drips/min × your taps at about 10,000 drips/gal (our estimate from EPA's 500+ gal/yr) | 3.79 | 1.44 | 526 | 1,990 | $5.26 |
| 1 drip/sec: 60 drips/min × your taps (USGS 15,140 drips/gal) | 15 | 5.71 | 2,083 | 7,885 | $20.83 |
| 1 drip/sec (60 drips/min) × your taps at about 10,000 drips/gal (our estimate from EPA's 3,000+ gal/yr) | 22.71 | 8.64 | 3,154 | 11,938 | $31.54 |
| Fast drip: 120 drips/min × your taps (USGS 15,140 drips/gal) | 30 | 11.41 | 4,166 | 15,770 | $41.66 |
| EPA average household leak total (9,300 gal/yr) | 66.98 | 25.48 | 9,300 | 35,204 | $93.00 |
| EPA severe household leak threshold (50 gal/day) | 131.44 | 50 | 18,250 | 69,084 | $182.50 |
Your leak wastes 2,083 gallons a year ($20.83). EPA's 9,300-gallon figure is the average for all leaks in a whole home, so this is 22 percent of that average. The drip rows multiply the drip rate by your 1 tap; at 60 drips/min per tap and USGS's 15,140 drips per gallon, that is 2,083 gallons a year.
How it works
On the USGS Water Science School Drip Calculator page, the agency notes: "There is no scientific definition of the volume of a faucet drip, but after measuring a number of kitchen and bathroom sink faucets, for our calculations below (numbers are rounded), we are going to use 1/4 milliliter (ml) as the volume of a faucet drip." From that 0.25 mL drop size, the USGS page lists "One gallon = 15,140 drips" and "One liter = 4,000 drips".
In Drip rate mode, we multiply drips per minute by 1,440 minutes a day and by your leaking taps. Then we divide that daily drop count by your drips per gallon setting to get gallons per day. Multiplying daily gallons by 365 days gives yearly water waste, and dividing yearly gallons by 12 gives monthly water waste.
In Measured catch mode, you catch the stream in a cup for 1 minute. Under NIST Handbook 44, Appendix C, 1 U.S. gallon is "231 cubic inches (exactly)". That equals "3 785.411 784 (exact)" mL or "3.785 411 784 (exact)" liters. We divide daily mL by 3,785.411784 to find gallons and by 1,000 to find liters. To convert larger pipe flows, open the Flow Rate Conversion Calculator.
Annual water loss is billed per kgal (one thousand gallons) or per CCF (one hundred cubic feet, or 748 gallons). Monthly gallons and monthly cost equal 1/12 of the yearly totals (30.42 days per month). That keeps monthly and yearly numbers in an exact 1-to-12 ratio.
Why USGS and EPA give different gallon totals for the same drip rate
A water drop does not have one fixed size. Drop size varies from tap to tap. On the USGS Water Science School Drip Calculator page, USGS uses 1/4 mL (0.25 mL) per drip. That equals 4,000 drips per liter and 15,140 drips per U.S. gallon (3,785.411784 ÷ 0.25 = 15,141.65, rounded to 15,140). At 1 drip a second (60 drips/min), the 15,140 factor gives 5.71 gallons a day and 2,083 gallons a year.
By contrast, the EPA WaterSense Fix a Leak Week page states: "A leaky faucet that drips at the rate of one drip per second can waste more than 3,000 gallons per year." On the same page, EPA adds: "A showerhead leaking at 10 drips per minute wastes more than 500 gallons per year." Note that 60 drips a minute is 31,536,000 drips a year, and 10 drips a minute is 5,256,000 drips a year. EPA does not state a drop size, but its numbers work out to a larger drop of about 0.36 to 0.38 mL (10,000 to 10,512 drips per gallon). That is our back-calculation, not an EPA figure. At 10,000 drips per gallon, 60 drips/min is 3,154 gallons a year and 10 drips/min is 526 gallons a year.
A smaller 0.05 mL drop (20 drops per mL) would come to 75,708 drops per U.S. gallon. You can enter any value from 1,000 to 100,000 in the Drips per U.S. gallon box. Type 15,140 for USGS, about 10,000 for the drop size implied by EPA's numbers, or your own tested drop count. The second table compares both drop sizes side by side, with each drip row counting your number of taps.
Federal faucet flow standards and household water benchmarks
Federal energy rules at 10 CFR 430.32(o) cap kitchen and bathroom sink faucets and aerators made after January 1, 1994. At 60 psi flowing pressure, their top flow is "2.2 gpm (8.3 L/min)", while metering taps cannot pass "0.25 gal/cycle (0.95 L/cycle)". On the EPA WaterSense Bathroom Faucets page, EPA writes: "WaterSense labeled bathroom sink faucets and accessories that use a maximum of 1.5 gallons per minute can reduce a sink's water flow by 30 percent or more from the standard flow of 2.2 gallons per minute without sacrificing performance." The same page says public rest room faucets "should have a flow rate of 0.5 gallons per minute or less to be considered efficient and meet plumbing code requirements". To price out a new aerator, try the Faucet Aerator Hot Water Savings Calculator.
Rules in 10 CFR 430.32(p), (q), and (r) cap showerheads at "2.5 gallons per minute (9.5 liters per minute)" at 80 psi. They also cap tank toilets at 1.6 gallons per flush and urinals at "1.0 gallons per flush (3.8 liters per flush)". On the EPA WaterSense Fix a Leak Week page, EPA states: "The average household's leaks can account for more than 9,300 gallons of water wasted every year and nine percent of homes have leaks that waste 50 gallons or more per day." On the EPA WaterSense Statistics and Facts page, EPA adds: "The average family can waste 180 gallons per week, or 9,400 gallons of water annually, from household leaks." The same page notes that each person uses "82 gallons of water a day at home". Compare normal use on the Household Water Demand Calculator, Toilet Water Savings Calculator, Shower Water Cost Calculator, and Bathtub Fill Calculator.
If the dripping tap is on the hot line, the leak also drains hot water from your tank. That forces your gas burner or electric element to fire again and again. Pass your daily gallon loss to the Water Heating Cost Calculator or check pipe storage on the Pipe Water Volume Calculator.
How utilities bill water and how to measure a fast trickle
City water systems bill homes in one of two units: 1,000 gallons (kgal) or 100 cubic feet (CCF). Under NIST Handbook 44, Appendix C, 1 cubic foot is "1 728 cubic inches (in3)" and "28.316 846 592" liters. One U.S. gallon is "231 cubic inches (exactly)". Dividing 172,800 cubic inches in 100 cubic feet by 231 cubic inches per gallon gives 748.0519 gallons. This tool bills a CCF as 748 gallons, which is 100 cubic feet rounded to whole gallons; check your bill for the unit your utility uses. Enter the sum of your water and sewer rates from your bill.
When the drops run together into a steady thread you cannot count by eye, switch the form to Measured catch (mL per minute) and hold a cup or spoon under the tap for 60 seconds. Under NIST Handbook 44, Appendix C, Section 5, "1 teaspoon, measuring" is "5 milliliters", and "1 tablespoon, measuring" is "15 milliliters". One "1 cup, measuring" is "8 fluid ounces (exactly)" or "237 milliliters". Filling a 15 mL spoon in 1 minute is 5.71 gallons a day; filling a 237 mL cup in 1 minute is 90.16 gallons a day (32,907 gallons a year).
Video walkthrough
A 3½-minute walkthrough of what a dripping faucet wastes in a year: gallons and cost, why USGS and EPA give different totals, more than one faucet, a trickle caught in a cup, and gallons against CCF.
Read the transcript
One drip a second
0:00 How much water does a dripping faucet waste, and what does it cost?
0:04 Take one faucet that drips once a second.
0:07 It wastes about 5.7 gallons a day, and about 2,100 gallons a year.
0:13 At $10 per 1,000 gallons, that is about $21 on your water bill.
0:18 Here is how the page gets there.
0:20 At 60 drips a minute, a faucet drips about 86,000 times a day.
0:26 Divide by the drips in a gallon, and you have the gallons a day.
0:30 Multiply by 365 days, and you have the year.
Why a drop has no one size
0:34 A drip has no official size.
0:37 USGS says so itself: there is no scientific definition of it.
0:41 For its calculator, USGS picks a quarter of a milliliter.
0:46 That drop makes 15,140 drips in a gallon, and it is the page's starting point.
0:52 You can change it in the form.
0:54 EPA gives a different total.
0:57 It says a faucet that drips once a second can waste more than 3,000 gallons a year.
1:02 That is more than the USGS total for the same drip.
1:06 One reason for the gap is drop size.
1:09 At about 10,000 drips in a gallon, a larger drop, the same leak comes to about 3,200 gallons a year.
1:16 That is our estimate of the drop behind EPA's number, not an EPA figure.
More than one faucet
1:23 Now count your faucets.
1:24 Change the faucet count to 3, each dripping once a second.
1:28 At USGS's drop size, the waste is about 6,200 gallons a year, and about $62 on the bill.
1:36 The page's drip rows multiply by your faucet count too.
1:40 With 3 faucets, the USGS row reads about 6,200 gallons, and our estimate row reads about 9,500 gallons.
1:50 For scale, EPA says the average household's leaks can account for more than 9,300 gallons a year.
1:57 These 3 faucets, at USGS's drop size, are about 67% of that.
Catch a stream in a cup
2:04 When the drops blur into a stream, you cannot count them.
2:08 Switch to measured catch.
2:09 Hold a cup under the faucet for a minute, and enter the milliliters you collect.
2:14 Now try a trickle.
2:15 Say you collect 25 milliliters in a minute.
2:18 That is about 9.5 gallons a day, and about 3,500 gallons a year.
2:25 At the same $10 per 1,000 gallons, the year costs about $35.
Gallons or CCF
2:31 Look at your bill for its unit.
2:33 The page offers these choices.
2:35 One is per 1,000 gallons.
2:38 The other is per CCF, which is 100 cubic feet.
2:42 The page counts that as 748 gallons.
2:45 The unit changes the cost.
2:48 Enter $10 per CCF, and the same leak costs about $28 a year.
2:53 Enter that rate per 1,000 gallons, and it costs about $21.
Test your own faucet
2:59 To test your own faucet, count the drips for a minute.
3:03 Enter that rate, the number of leaking faucets, and the rate from your bill.
3:07 To check for a leak you cannot see, EPA suggests reading your water meter before and after 2 hours with no water being used.
3:15 If the meter changes at all, you probably have a leak.
3:19 EPA says common leaks include worn toilet flappers and dripping faucets.
3:24 So remember: the drop size is an estimate, and the drip rows count every faucet.
3:29 Match your bill's unit, and try your own faucet at fastcalc.us.
Formula
daily gallons (drips) = (drips per minute × 1,440 × fixtures) ÷ drips per gallon daily gallons (measured) = (mL per minute × 1,440 × fixtures) ÷ 3,785.411784 daily liters = daily gallons × 3.785411784 annual gallons = daily gallons × 365 monthly gallons = annual gallons ÷ 12 annual cost = (annual gallons ÷ unit gallons) × combined rate (unit gallons = 1,000 for kgal, 748 for CCF) monthly cost = annual cost ÷ 12
Example
One tap dripping once per second (60 drips/min) gives 60 × 1,440 = 86,400 drips a day. Dividing 86,400 by 15,140 drips per gallon gives 5.71 gallons a day (21.60 L/day) and 173.6 gallons a month. Over 365 days, that single tap wastes 7,885 L a year and costs $1.74 a month ($20.83 a year) at $10.00 per kgal.
Three taps dripping at 30 drips a minute each drop 30 × 1,440 × 3 = 129,600 times a day. That is 8.56 gallons a day (32.40 L/day) and 3,124 gallons a year (11,827 L/year). Billed by CCF at $9.50 per 748 gallons, the bill adds (3,124.44 ÷ 748) × $9.50 = $39.68 a year ($3.31 a month).
A steady trickle caught in a cup at 25 mL a minute loses 25 × 1,440 = 36,000 mL a day (36.00 L/day). Dividing by 3,785.411784 mL per gallon gives 9.51 gallons a day and 289.3 gallons a month. Over a year, it wastes 3,471 gallons (13,140 L) and costs $41.65 at $12.00 per 1,000 gallons.
Assumptions and limitations
- Steady 24-hour leak rate: Daily waste multiplies the per-minute rate by 1,440 minutes a day. Yearly waste multiplies the daily rate by 365 days a year. This matches the USGS Water Science School Drip Calculator page script (Dripsday = 1440 × drips × faucets × homes; Gallonsyear = Gallonsday × 365). Pipe pressure swings between day and night are not modeled.
- USGS prose versus script conversion note: The USGS Water Science School Drip Calculator page text prints "One gallon = 15,140 drips" and "One liter = 4,000 drips". Its page script divides daily drips by 4,000 for liters and then divides liters by 3.785 for gallons (4,000 × 3.785 = 15,140). Here, we divide daily drips by your Drips per U.S. gallon input (default 15,140) for gallons. Then we multiply gallons by the exact NIST Handbook 44, Appendix C factor of 3.785411784 L/gal (giving 3,999.56 drips/L at 15,140 drips/gal).
- Equal 1/12-year months: Monthly water loss and monthly cost both equal 1/12 of the 365-day yearly totals (30.42 days per month). Twelve months therefore sum to 100% of the yearly volume and cost.
- Volume charges only: Cost figures multiply wasted gallons by your combined water and sewer rate per kgal or per CCF. Fixed monthly base fees, tiered block jumps, and water heater fuel are not included here.
What to do with the result
Run the two-hour meter test: On the EPA WaterSense Fix a Leak Week page, EPA advises: "Check your water meter before and after a two-hour period when no water is being used. If the meter changes at all, you probably have a leak." Also check winter bills: "If a family of four exceeds 12,000 gallons per month, there could be serious leaks."
Shut off the stops and swap worn seals: As the EPA WaterSense Fix a Leak Week page notes, "Old and worn faucet washers and gaskets frequently cause leaks in faucets." Close the shutoff valves under the sink. Then put in a new stem washer, O-ring, ceramic disc, or cartridge, since one drip a second wastes about 2,083 gallons a year.
Screw on a 1.5 gpm WaterSense aerator: While working on the tap, rinse grit from the screen or fit a 1.5 gpm WaterSense bathroom aerator. That cuts active tap flow by at least 30 percent below the 2.2 gpm limit in 10 CFR 430.32(o). An EPA draft specification would lower the WaterSense cap for private lavatory faucets to 1.2 gpm.
Check if the drip is warm: A hot-water leak wastes both water and water-heater fuel, and 5.71 gallons a day of it adds up. Send your daily gallons to the Water Heating Cost Calculator to see the energy cost.
Frequently asked questions
How many drips are in a gallon of water?
On the USGS Water Science School Drip Calculator page, USGS uses a drop size of 1/4 milliliter. That gives "One gallon = 15,140 drips" and "One liter = 4,000 drips". On the EPA WaterSense Fix a Leak Week page, EPA cites "more than 3,000 gallons per year" at 1 drip per second. EPA gives no drop size, but that figure works out to a larger drop of about 3/8 milliliter (our back-calculation). Enter any drop count in Drips per U.S. gallon to match your spout.
How much water does a faucet dripping once per second waste in a day and a year?
One drip a second is 60 drips a minute. Under the USGS 15,140 drips-per-gallon standard, 1 tap wastes 5.7067 gallons a day before rounding and 2,082.96 gallons a year. At about 10,000 drips per gallon (our estimate of the drop size behind EPA's 3,000-gallon mark), 1 drip a second wastes 8.64 gallons a day and 262.8 gallons a month.
How much does a dripping faucet add to a water and sewer bill?
Multiply your yearly gallons by your combined water and sewer rate per billing unit. Three taps dripping once a second (6,249 gallons a year total) cost $62.49 a year at $10.00 per kgal, or $5.21 a month. In high-rate cities charging $20.00 per kgal, those 3 taps cost $124.98 a year ($10.42 a month).
How do I measure a faucet leak that has turned into a steady stream?
When drops merge into a stream, set How to enter the leak to Measured catch (mL per minute). Catch the water in a spoon or cup for 60 seconds. Under NIST Handbook 44, Appendix C, 1 teaspoon is 5 mL, 1 tablespoon is 15 mL, and 1 cup is 237 mL. Type the 1-minute catch in mL to find your daily, monthly, and yearly loss.
What is the difference between kgal and CCF on a water bill?
One kgal is one thousand U.S. gallons. One CCF is one hundred cubic feet of water, which this tool counts as 748 gallons (check your bill for your utility's unit). Under NIST Handbook 44, Appendix C, 1 cubic foot is 1,728 cubic inches. Because 1 CCF is smaller than 1 kgal, a rate of $7.48 per CCF equals $10.00 per kgal, and $10.00 per CCF equals $13.37 per kgal.
What is the federal flow-rate limit for a working kitchen or bathroom faucet?
Under Department of Energy rules at 10 CFR 430.32(o), kitchen and bathroom faucets and aerators made after January 1, 1994 cannot pass "2.2 gpm (8.3 L/min)" at 60 psi. Left wide open at 2.2 gpm, a tap flows 132 gallons an hour (3,168 gallons a day). On the EPA WaterSense Bathroom Faucets page, WaterSense labeled bathroom sink faucets can cut a sink's flow by "30 percent or more" without sacrificing performance. EPA's WaterSense label covers private bathroom and bar sink faucets, not kitchen faucets.
Sources
- USGS Water Science School, Drip Calculator: How Much Water Does a Leaking Faucet Waste? (current version)
- EPA WaterSense, Fix a Leak Week (page modified Mar 13, 2026)
- EPA WaterSense, Bathroom Faucets (page modified Jun 16, 2026)
- EPA WaterSense, Statistics and Facts (page modified Mar 11, 2026)
- 10 CFR 430.32, Energy and Water Conservation Standards and Their Compliance Dates (GovInfo 2024 CFR) (page modified Jan 1, 2024)
- NIST, Handbook 44 (2026), Appendix C, General Tables of Units of Measurement (page modified Dec 22, 2025)
More in Kitchen & Bath Calculators and Home Improvement Calculators.