What this calculator works out
This calculator converts daily water use in litres into a cost over a chosen number of days, at a price per cubic metre.
It applies only to metered supplies. On an unmetered supply the bill is based on rateable value and does not change with consumption at all.
Enter your details
Before you calculate
- Take the price from a recent bill. Most bills charge separately for supply and for wastewater, and the combined figure is what matters for most household use.
- Typical UK consumption is around 140 litres per person per day, so a household of two or three uses roughly 280 to 420 litres.
- A cubic metre is 1,000 litres, which is how water is billed.
- Water used outdoors is charged for supply but may not attract the wastewater charge, since it does not return to the sewer.
Showers and baths typically account for the largest share, followed by toilet flushing, then washing machines and dishwashers. Drinking and cooking are a very small fraction. That means the effective savings are in shower length and toilet flush volume rather than in running the tap less while brushing teeth.
How this calculator works
Litres to cubic metres, then to money:
Cost = daily litres ÷ 1,000 × price per m³ × daysDividing by 1,000 converts litres to cubic metres. Entering 365 days gives an annual figure; entering 1 gives a daily one, which is useful for costing an individual behaviour such as a long shower.
Worked example: 350 litres a day
Using the default figures — 350 litres a day at £2.20 per cubic metre, over 365 days:
- Annual consumption: 127.75 m³
- Annual cost: £281.05
Now cost a single behaviour. A power shower using 15 litres a minute for ten minutes is 150 litres, or 33p. Reducing that to five minutes saves 17p a shower — around £60 a year for one person showering daily. That is the kind of figure that makes a shower timer worth having, and it is invisible until the arithmetic is done.
Common mistakes
- Assuming a saving on an unmetered supply. The bill does not respond to consumption.
- Using only the supply rate. Most indoor use also attracts a wastewater charge.
- Estimating consumption rather than reading the meter. Two readings a week apart give a real figure.
- Focusing on taps rather than showers. Showers and toilets dominate household use.
- Forgetting leaks. A dripping tap or leaking toilet can waste thousands of litres a year.
Frequently asked questions
Should I switch to a water meter?
Broadly, if there are fewer people in the house than bedrooms, a meter usually saves money. Most water companies allow a trial period of a year or two during which you can revert if the bill goes up. Comparison calculators from your supplier give a more reliable answer than any rule of thumb.
How do I check for a leak?
Turn off every water-using appliance and tap, then read the meter, wait an hour or two with no use, and read it again. Any movement indicates a leak. A leaking toilet is the most common culprit and often silent — putting a little food colouring in the cistern and checking whether it reaches the pan will confirm it.
How much water does a shower use?
An electric shower typically uses 6 to 10 litres a minute; a mixer shower on a combi boiler 10 to 12; a power shower with a pump 15 or more. A bath is around 80 litres. A ten-minute power shower therefore uses considerably more than a bath, contrary to the usual assumption.
Does a water butt reduce the bill?
On a metered supply, yes, for the water it replaces — though garden watering is a small share of most households' consumption. The Water Butt Savings Calculator quantifies it. On an unmetered supply there is no financial saving, only the environmental one.
Is what I enter stored?
No. Figures are processed in your browser and never transmitted or retained.
Related tools
References
- GOV.UK — water metering, water efficiency and help with water bills
- MoneyHelper — guidance on water bills and social tariffs
Sources are checked at publication and can change — how I choose and check references.