How do I measure my leak's actual rate?

For a faucet, time how long it takes to fill a measured container (a 250 ml cup or a 1-cup measure) and convert to litres or gallons per minute. For a running toilet, add a few drops of food coloring to the tank — if it appears in the bowl without flushing, it's leaking, and a bucket test under the fill valve can estimate the rate.

Where do I find my water rate?

On your utility bill, as a volumetric charge — typically quoted per cubic meter (per kilolitre in some regions) or per 1,000 gallons in the US. Switch the unit system above and enter it exactly as billed.

Does a small drip really cost anything?

A slow drip wastes surprisingly little money on its own — often only a few dollars a year — but leaks tend to worsen, and toilets that run intermittently are easy to underestimate. The bigger risk from any persistent leak is moisture damage, not the water bill.

Financial-Adjacent

Water Leak Cost Calculator

Estimate the annual cost of a running toilet or dripping fixture based on its leak rate.

Answers as you typeNo submit button
Every formula citedNamed published standards
Calculated in your browserNo account, nothing uploaded

SettingsSettings for this calculationUS

Market

Imperial · sales tax

Leak Rate

How fast the leak flows, in the unit shown.

A running toilet is commonly cited around 0.125 L/min (about 0.033 gal/min); a steady faucet drip is often much smaller. Time a container filling under the leak to measure your specific rate.

Water Rate

Your local water utility's volumetric rate, in the unit shown.

Check a recent water bill — rates vary widely by municipality and often include separate sewer charges based on water usage too. Typical municipal rates run roughly 0.5–3 per m³ (about 2–11 per 1,000 gallons).

Water wasted per year

17,400 gal

Medium confidence

Figures that depend on a rate wait for yours — this page does not assume one.

Then change the inputs to see how far the answer moves.

Show calculation logic

How this was calculated

Formula source(s)

Annual volume wasted = leak rate × minutes per year; annual cost = volume wasted × your utility's volumetric water rate

Inputs used

Leak Rate: 0.03 gal/min
Water Rate

Final result17,356.1 gal

What this calculation does not cover

A leak on the hot side costs the water and the energy that heated it. Raising the same volume 40-50 °C (70-90 °F) at typical fuel prices runs several times the water charge itself, so a dripping mixer or a hot supply weeping past a valve is mostly a fuel bill wearing a water bill's clothes. This figure sees only the volume.
The result runs the entered rate for all 525,600 minutes in the year. A flapper that only weeps for a while after each flush, an irrigation line that is only live in season, or a leak that has been steadily worsening each has a duty cycle, and cost scales straight in proportion to it — time the minutes it actually runs in a day and pro-rate, rather than accepting the continuous-flow assumption baked in here.

Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.

Sources checked 2026-09-06 · in the site-wide review of 2026-09-06 · v1.1.1

Regulatory standards & verification citations1

Annual volume wasted = leak rate × minutes per year; annual cost = volume wasted × your utility's volumetric water rate

Cite this page

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Now that you have the number

These guides cover the work this quantity is for — the first ones run this calculator inside the section that raises the question.

Costing a Bathroom by Fixture and Wet Areauses this calculator
A bathroom is priced through a fixture count and two areas measured to different rules. Floor area is not one of them, and the leak is not a saving.
Finding What Is Driving a High Water Billuses this calculator
A bill twice the usual size is a leak, a tariff block or an estimated read. Telling which takes an hour at the meter and a dye tablet upstairs.
Fixing Dry Spots in a Lawn

Called something else where you work? Cistern and water storage — the term in each market, how close the equivalence really is, and the standard that governs it.

Already gone wrong? My toilet keeps running or trickling · My tap drips or leaks · My toilet flushes weakly, or needs two goes · Water is running from an overflow pipe outside my house · I have no water, or a pipe has frozen

How to calculate water leak cost in 3 steps

Leak RateHow fast the leak flows, in the unit shown.
Water RateYour local water utility's volumetric rate, in the unit shown.
Estimated annual costThe tool computes the estimated annual cost from those figures and shows the formula, its sources, and a confidence rating alongside it.

Frequently asked questions

How do I measure my leak's actual rate?: For a faucet, time how long it takes to fill a measured container (a 250 ml cup or a 1-cup measure) and convert to litres or gallons per minute. For a running toilet, add a few drops of food coloring to the tank — if it appears in the bowl without flushing, it's leaking, and a bucket test under the fill valve can estimate the rate.
Where do I find my water rate?: On your utility bill, as a volumetric charge — typically quoted per cubic meter (per kilolitre in some regions) or per 1,000 gallons in the US. Switch the unit system above and enter it exactly as billed.
Does a small drip really cost anything?: A slow drip wastes surprisingly little money on its own — often only a few dollars a year — but leaks tend to worsen, and toilets that run intermittently are easy to underestimate. The bigger risk from any persistent leak is moisture damage, not the water bill.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — a confirmed fix gets a permanent check of its own, so the same mistake cannot come back.