How this instrument works
A dripping faucet looks trivial — a drop every second or two barely seems worth fixing. The US EPA's WaterSense program built a reference figure specifically to correct that intuition: a faucet dripping at one drip per second (60 drips a minute) can waste more than 3,000 gallons of water in a year, roughly the amount needed for more than 180 showers.
This calculator scales linearly from that single EPA reference point: since 60 drips per minute wastes about 3,000 gallons a year, each drip per minute corresponds to about 50 gallons a year (3,000 ÷ 60), so any drip rate you measure can be converted straight into an annual waste figure without needing a stopwatch and a measuring cup.
The result is shown in both US gallons and litres, using the exact NIST conversion factor of 3.785411784 litres per gallon, so the number is useful whichever unit system you think in.
- Time your faucet for a few seconds and count the drips to estimate a per-minute rate.
- Enter Drips per minute — your measured or estimated drip rate.
- Read Water wasted per year in US gallons.
- Read Water wasted per year in litres.
Worked example — the EPA's own reference drip rate
A faucet dripping once per second — 60 drips a minute, the EPA WaterSense program's own headline reference case — wastes 60 × 50 = 3,000 gallons of water a year, matching the EPA's published figure exactly. Converted to litres, that's 3,000 × 3.785411784 ≈ 11,356 litres a year from a single leaky tap.
A slower, easy-to-ignore drip of 15 drips a minute — about one drip every four seconds — still wastes 15 × 50 = 750 gallons (roughly 2,839 litres) a year, a quarter of the reference case but still a meaningful amount of wasted water and, indirectly, the energy used to treat and pump it.
Questions
How much water does a dripping faucet actually waste in a year?
The EPA WaterSense program's reference case — a faucet dripping once per second, or 60 drips a minute — wastes more than 3,000 gallons (about 11,356 litres) a year, equivalent to more than 180 showers' worth of water from a single leak. Slower or faster drips scale proportionally from that reference point.
How do I count drips per minute without a stopwatch?
Count the drips over a 15-second window using a phone timer, then multiply by 4 to get a per-minute rate — or count over 10 seconds and multiply by 6. Faucet drip rates can vary a bit from moment to moment, so counting over at least 10-15 seconds gives a steadier estimate than trying to count for just one second.
Does this account for hot-water drips wasting energy too?
No — this calculator only totals the water volume wasted, not any energy cost. A dripping hot-water tap wastes both the water and the energy already spent heating it, so a hot-water drip is more costly overall than a cold-water drip of the same rate, even though this tool reports the same water-volume figure for either.
Is a slow, barely-audible drip still worth fixing?
Yes — even a very slow drip of just 1 drip per minute still wastes about 50 gallons (roughly 189 litres) a year by this calculation, and most leaky faucets drip faster than that once you actually count. Most faucet drips are caused by a worn washer or O-ring, which is typically an inexpensive, quick fix compared with the water wasted by leaving it unaddressed.
Where does the '50 gallons per drip per minute' figure come from?
It's derived directly from the EPA WaterSense program's own published reference: a 60-drips-per-minute faucet wastes more than 3,000 gallons a year, so dividing 3,000 by 60 gives roughly 50 gallons per year for each additional drip per minute, assuming a fairly constant drip rate over the full year. It's a linear scaling from one well-documented reference point rather than a separately measured rate for every possible drip speed.