How to use this calculator
- Count drips for 15 seconds and multiply by 4 to get drips per minute.
- Enter how many taps leak at a similar rate.
- Keep the default drop size unless you have measured it.
- Read the daily, monthly and yearly loss.
How much water does a dripping tap waste?
Loss (L/day) = drips/min × 1,440 × drop volume (mL) ÷ 1,000 × taps
1,440 is the number of minutes in a day. The USGS drip calculator assumes 15,140 drips per US gallon, which is 0.25 mL per drop.
Worked example
With drips per minute 30, number of leaking taps 1, volume of one drop 0.25 mL, water tariff 20 ₹ per kL:
Water wasted per year: 3,942 litres
The calculator also gives per day 10.8 L; per month 324 L; drinking water for one person 1,314 days.
Assumptions and limits
- Assumes the drip rate is steady all day.
- Drop size varies with tap design and pressure, so treat results as an estimate.
- A thin continuous stream is not a drip; it can waste over 100 litres a day.
Frequently asked questions
How many drips make a litre?
About 4,000 drops make a litre at 0.25 mL per drop.
How much water does one drip per second waste?
One drip per second (60 per minute) wastes about 21.6 litres a day, or almost 7,900 litres a year.
How do I fix a dripping tap?
Turn off the supply, open the tap head and replace the rubber washer or ceramic cartridge. Check the valve seat for wear if it keeps dripping.
References
- USGS Water Science School, Drip Calculator
- BIS IS 1172:1993, basic water requirements