Water Leak Cost Calculator
Quantifies the water wasted and money lost from household leaks like dripping faucets and running toilets. Ideal for convincing homeowners to prioritize repairs or benchmarking against utility bills.
Last updated: September 2026
Formula below · 2 sources (epa.gov, Wikipedia) · Updated Sep 2026
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About this calculator
The formula models a leak at a constant flow rate and calculates accumulated waste over time: Total cost = (leak rate in gal/min × 1,440 min/day × days leaking ÷ 1,000) × (waterRate + sewerRate). Dividing by 1,000 converts gallons to the standard billing unit of 1,000 gallons. The sewer rate is added because most utilities charge sewer fees based on metered water consumption, effectively doubling the cost of waste. The leak-type selector sets the flow: a faucet dripping once per second wastes about 3,000 gallons a year according to the EPA (about 0.0057 gal/min), a running toilet can waste about 200 gallons a day (about 0.14 gal/min), a steady stream from a cracked fitting is about 0.5 gal/min, and a broken pipe or irrigation line 2 gal/min or more. A single drip costs only dollars a year, but a running toilet or steady stream can cost hundreds.
How to use
Assume a steady 0.5 gal/min leak (for example a cracked fitting) has been running for 30 days, your water rate is $5.00/1,000 gal, and your sewer rate is $4.00/1,000 gal. Cost = (0.5 × 1,440 × 30 ÷ 1,000) × (5.00 + 4.00) = (21,600 ÷ 1,000) × 9.00 = 21.6 × 9.00 = $194.40. That leak wasted 21,600 gallons and cost nearly $200 in one month. A running toilet (0.14 gal/min) over the same 30 days costs about $54.43, and a faucet dripping once per second about $2.22. Select your leak type, enter the number of days and your local rates to see your actual cost.
Frequently asked questions
How much water does a dripping faucet waste per month?
A faucet dripping once per second wastes about 3,000 gallons per year (about 250 gallons per month), according to the EPA. A steady 0.5 gallon-per-minute stream is a far bigger leak: over 21,000 gallons per month. The EPA estimates that household leaks collectively waste nearly 1 trillion gallons of water annually in the United States. A dripping faucet adds only a few dollars a month, but a running toilet or steady stream can add $50 to $200 a month depending on local rates.
Why does my water bill include sewer charges for water I never put down the drain?
Most municipalities calculate sewer fees based on metered water intake under the assumption that nearly all incoming water eventually returns to the sewer system. This means every gallon you waste to a leak is billed twice — once as water supply and once as sewage. Some utilities offer irrigation meters or sewer-cap programs for outdoor water use that doesn't enter the drain. Checking with your utility about such programs can reduce the effective cost of outdoor leaks.
When is it worth fixing a small leak versus calling a plumber?
A dripping faucet can often be fixed with a $5 washer in under 30 minutes, making the repair cost-effective almost immediately. Running toilets typically require a flapper replacement ($10–$20) and can save $50 or more per month. If a leak involves pipe corrosion, hidden wall damage, or pressure issues, a licensed plumber is warranted to prevent structural damage that far exceeds water bill savings. As a rule of thumb, any leak that has been running more than two weeks should be repaired regardless of apparent flow rate.