How much water does a dripping faucet really waste?
A dripping faucet looks trivial, but the drips add up fast because they never stop. This calculator multiplies your drip rate by the volume of a single drop, then scales that up to gallons or liters per day, month, and year — the same basic method utilities and plumbers use to estimate leak losses. The formula is: Water wasted = drips per minute × mL per drip × 1,440 minutes/day, converted to gallons (1 US gallon = 3,785.41 mL) or liters (1 L = 1,000 mL).
The reference benchmark
The U.S. Environmental Protection Agency's WaterSense program cites a widely used benchmark: a faucet dripping at a rate of one drip per second wastes roughly 3 gallons (about 11.4 liters) per day — about 1,090 gallons (over 4,100 liters) per year. One drip per second equals 60 drips per minute, which works back to a typical drop volume of about 0.13 mL per drip. That 0.13 mL default is what this calculator starts with, but actual drop size varies by faucet design, washer wear, and water pressure — anywhere from about 0.05 mL for a fine seep to 0.36 mL or more for a fat, slow drop (some larger drips can waste 3,000+ gallons a year) — so adjust it if you can measure your own drip (see below).
How to measure your own drip rate
Place a measuring cup or clear glass under the leak and time it with a phone stopwatch. Count the number of drips in 60 seconds to get "drips per minute," or measure the volume collected over 10–15 minutes to back-calculate the mL-per-drip figure directly (volume in mL ÷ number of drips = mL per drip). The more precise this input is, the more accurate the yearly total and cost estimate will be.
Reference points for context
- 1 drip per second (60 drips/min) ≈ 3 gallons/day ≈ 1,090 gallons/year ≈ 4,127 liters/year.
- 1 drip every 2 seconds (30 drips/min) ≈ 1.5 gallons/day ≈ 545 gallons/year.
- A faster, visible trickle (120+ drips/min or a thin stream) can waste 6+ gallons/day — over 2,000 gallons a year, comparable to dozens of extra showers.
- US public water supply typically costs $2–$10 per 1,000 gallons depending on location and utility, which this calculator uses to estimate the annual dollar cost.
Why fixing the drip matters
Beyond the water bill, a persistent drip on a hot-water tap also wastes the energy used to heat that water, and constant dripping can stain fixtures, waste a washer or O-ring faster, and eventually damage cabinetry or flooring from moisture. Most faucet drips are caused by a worn rubber washer, O-ring, or valve seat and are inexpensive, quick repairs — a few dollars in parts pays for itself in water savings within weeks for even a slow drip.