Show the formula and working
This dripping tap cost calculator works out how much water a leaking tap wastes per day and per year, and what it costs on a metered water bill in the UK or Europe. Count the drips for one minute, enter your water and sewerage price, and it shows litres, cubic metres and the yearly cost. Tick the hot tap option to add the energy cost of heating the wasted water.
Quick answer: Multiply drips per minute by 1,440 minutes and by 0.25 ml per drip to get litres a day. One drip a second wastes 21.6 litres a day, or 7,884 litres a year. At an example £4.00 per m³ the dripping tap cost calculator shows £31.54 a year, and about double that for a hot tap.
What Is a Dripping Tap Cost Calculator?
A dripping tap cost calculator is a tool that turns a drip rate into the volume of water wasted and its cost. The formula in plain words: litres per day = drips per minute x 1,440 minutes x the volume of one drip in millilitres / 1,000. Litres per year = litres per day x 365, and cost = cubic metres per year x your water and sewerage price per cubic metre.
There is no official size for a drip. The US Geological Survey drip calculator uses 0.25 ml per drip, which is 4,000 drips per litre, based on its own measurements of kitchen and bathroom taps. The calculator uses that figure by default and lets you change it.
How Do You Use the Dripping Tap Cost Calculator?
- Count the drips for one full minute and enter the number in Drips per minute.
- Leave Volume of one drip at 0.25 ml, or change it if you have measured your own drips.
- Enter the Number of dripping taps.
- Add your Water and sewerage price per cubic metre (example) from your water bill.
- If hot water is dripping, tick It is a hot tap and check the Hot water temperature rise, Water heater efficiency and Energy unit rate for hot water.
- Read the yearly cost and litres wasted, then open “Show the formula and working” to see each step.
How Much Water Does a Dripping Tap Waste?
A tap dripping once a second wastes about 21.6 litres a day and 7,884 litres a year, using 0.25 ml per drip. That is close to 8 cubic metres of water. Faster drips waste proportionally more: two drips a second doubles the figure. Once drips join into a thin stream, the waste can be far higher, so measure a trickle with a jug and a timer instead.
| Drip rate | Litres per day | Litres per year | Cost per year at £4.00 per m³ |
|---|---|---|---|
| 10 per minute | 3.6 | 1,314 | £5.26 |
| 30 per minute | 10.8 | 3,942 | £15.77 |
| 60 per minute (1 a second) | 21.6 | 7,884 | £31.54 |
| 120 per minute (2 a second) | 43.2 | 15,768 | £63.07 |
| 300 per minute (5 a second) | 108.0 | 39,420 | £157.68 |
The £4.00 per m³ price is an example only. Add together the water supply and sewerage prices per cubic metre on your own bill.
Does a Dripping Tap Cost Money If I Am Not on a Meter?
If your water is unmetered, a dripping tap does not change your water bill, because you pay a fixed charge based on your property rather than the water you use. It still wastes water, and a dripping hot tap still costs you money in gas or electricity to heat it. On a water meter you pay for every litre, plus sewerage on the water that goes down the drain.
How Much Does a Dripping Hot Tap Cost?
A hot tap dripping once a second costs about £32 a year to heat on top of the water cost, with a 40 °C rise, a 90% efficient gas boiler and the Ofgem cap gas rate of 7.97p per kWh. Heating 7,884 litres by 40 °C takes about 407 kWh of gas. The Ofgem price cap announcement gives the rate for 1 October to 31 December 2026. With an immersion heater at 26.32p per kWh the heating cost is far higher, and the immersion heater cost calculator shows how that adds up.
How Do You Fix a Dripping Tap?
Most drips come from a worn washer in a traditional tap or a worn ceramic cartridge in a quarter turn tap, and both parts are cheap to replace. Turn off the water at the isolating valve under the sink or at the stopcock first, and open the tap to drain it. If you are not confident, or the tap body is damaged, ask a plumber. To see what other appliances and hot water cost to run, browse our energy bill calculators.
Worked Example: Cost of a Tap Dripping Once a Second
Example: one cold tap drips 60 times a minute, the drip size is the USGS figure of 0.25 ml, and the household pays an example combined water and sewerage price of £4.00 per m³. These are the calculator’s default inputs.
- Water per day: 60 x 1,440 x 0.25 ml = 21,600 ml, which is 21.6 litres.
- Water per year: 21.6 litres x 365 = 7,884 litres, which is 7.88 m³.
- Cost per year: 7.884 m³ x £4.00 = £31.54.
If the same drip is from a hot tap heated by a 90% efficient gas boiler with a 40 °C rise at 7.97p per kWh, heating adds about 407 kWh and £32.45, so the total is £63.99 a year.
Dripping Tap Cost Calculator FAQs
How many drips are in a litre?
Using the US Geological Survey figure of 0.25 ml per drip, there are 4,000 drips in a litre. Drip size varies with the tap and water pressure, so the calculator lets you change the drip volume if you have measured your own.
How much does a dripping tap cost per year?
A tap dripping once a second wastes about 7,884 litres a year, which costs about £31.54 at an example water and sewerage price of £4.00 per m³. A hot tap costs more, because the water has to be heated as well.
How do I measure the drip rate?
Watch the tap with a phone timer and count the drips for one full minute. For a faster drip or a trickle, hold a measuring jug under the tap for one minute and read the millilitres, then divide by the drip count.
Why is sewerage included in the price?
On a metered supply most water companies charge for the water you take and for the waste water that goes down the drain. A dripping tap sends nearly all its water to the sewer, so both charges apply. Use the two prices per m³ from your bill.
Is a dripping tap an emergency?
A dripping tap is not an emergency, but it is worth fixing soon because the waste adds up. A leak from a pipe, a tap body or under a sink that you cannot stop is more urgent. Turn off the stopcock and call a plumber.
Can a dripping tap raise my energy bill?
Yes, if it is a hot tap. Every litre that drips has been heated by your boiler, immersion heater or water heater. Tick the hot tap option in the calculator to see the extra energy and its yearly cost.
Checked October 2026. Sources: USGS Water Science School: drip calculator (0.25 ml per drip), Ofgem: energy price cap 1 October to 31 December 2026, Wikipedia: Specific heat capacity (water 4.184 kJ per kg per °C).