Dripping Tap Water Loss Calculator (What a Leak Costs)
Litres a dripping tap or running toilet wastes per day, month and year, and what that costs at your water price.
Results
The dashed line marks the value you entered.
What this tool does
A drop is small, but there are a lot of them: 30 drips a minute at 0.1 mL each is 4.3 litres a day, or 1.6 cubic metres a year, and a thin continuous stream at 0.1 L/min is 144 litres a day. The size of a drip varies with the tap and the pressure, commonly 0.05 to 0.3 mL, so measure it: catch the drips in a measuring jug for ten minutes and divide. A running toilet is usually the biggest hidden leak in a home; a few drops of food colouring in the cistern will show if it is leaking into the bowl.
Formula
litres per day = drips per minute × volume of a drip (mL) × 1440 ÷ 1000 + trickle (L/min) × 1440 · m³ per year = litres per day × 365 ÷ 1000
Variables
| Symbol | Meaning | Unit |
|---|---|---|
dr | Drips per minute | 1/min |
dv | Volume of one drip | mL |
tl | Constant trickle (running toilet or thin stream) | L/min |
wp | Water price per cubic metre | — |
LD | Water lost per day | L |
LM | Water lost per month | L |
MY | Water lost per year | m³ |
CY | Cost of the leak per year | — |
Worked example
- Drips per minute30 1/min
- Volume of one drip0.1 mL
- Constant trickle (running toilet or thin stream)0 L/min
- Water price per cubic metre2.5
- Water lost per day4.3 L
- Water lost per month131 L
- Water lost per year1.6 m³
- Cost of the leak per year3.94
Limitations
- The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.
- Prices and emission factors are yours to enter. The tool ships with no tariff table and assumes nothing about your country or supplier, so change the defaults to match your own bill.