About the Water Usage Calculator
Water comes out of the tap so easily that few people know how much they use. Yet a typical household uses hundreds of litres a day, and in places with water meters every litre is on the bill — often twice, once for the clean water coming in and again for the waste water going out. Knowing where the water goes is the first step to saving it, whether the goal is a lower bill, getting through a hosepipe ban, or reducing your environmental footprint.
This water usage calculator estimates your household's daily water use from its main uses: showers, baths, toilet flushes, laundry, the dishwasher, the garden hose, and everyday taps and cooking. It gives the total in litres and US gallons, the use per person, the monthly and yearly volume in cubic metres, the cost at your water price, and which use is the biggest.
How to Use the Water Usage Calculator
Enter the number of people in the household.
Enter the showers a day for the whole household, the minutes per shower and the shower's flow rate in litres per minute.
Enter the baths a week, the toilet flushes per person a day and the litres per flush.
Enter the washing machine and dishwasher loads a week and the garden hose minutes a week.
Enter your water price per cubic metre to see the cost.
How Water Use Is Worked Out
showers = showers a day × minutes × litres per minute
baths = baths a week × 80 L ÷ 7
toilet = people × flushes each × litres per flush
laundry = loads a week × 50 L ÷ 7
dishwasher = loads a week × 12 L ÷ 7
garden = hose minutes a week × 15 L ÷ 7
taps = people × 15 L
a month = total a day × 30 ÷ 1,000 (m³)Step-by-Step Example
Four people, four 8 minute showers a day at 8 L/min, two baths a week, five flushes each at 6 L, five laundry loads and seven dishwasher loads a week, water at 2.00 per m³.
Showers: 4 × 8 × 8 = 256 L
Baths: 2 × 80 ÷ 7 = 23 L
Toilet: 4 × 5 × 6 = 120 L
Laundry: 5 × 50 ÷ 7 = 36 L
Dishwasher: 7 × 12 ÷ 7 = 12 L
Taps: 4 × 15 = 60 L
Total: = about 507 L a day (127 L each)
A month: 507 × 30 ÷ 1,000 = 15.2 m³ → 30.39
A year: = 185 m³ → 369.80Where the Water Goes
In most homes, showers and baths are the biggest use, followed by toilets. In the example, showers alone are half the total. Washing machines and dishwashers are smaller than many people expect, because modern machines are very efficient. Outdoor use varies enormously: an hour of watering with a hose uses about 900 litres, more than the whole household uses indoors in a day, which is why gardens dominate water use in hot, dry summers.
Typical Water Use Per Person
Average household use varies by country and climate. In the UK, average use is around 140 litres per person a day; in much of Europe it is lower; in the United States, indoor use is typically around 225 to 300 litres, and much more where lawns are watered. Many water companies aim to bring use down towards 110 litres per person, which is quite achievable with efficient fittings and habits.
Ways to Save Water
Shorter showers: cutting a shower from 8 minutes to 5 saves 24 litres at 8 litres a minute.
A low-flow shower head: 6 litres a minute instead of 10 saves 32 litres on an 8 minute shower, with little difference in feel.
Dual-flush or efficient toilets: replacing an old 13 litre toilet with a 4.5 litre dual-flush model can save tens of litres per person a day. A cistern displacement bag is a cheap alternative.
Full loads: run the washing machine and dishwasher only when full.
Fix leaks: a dripping tap can waste over 5,000 litres a year, and a leaking toilet many times more.
Water the garden wisely: water early or late, at the roots, and use a watering can or collected rainwater instead of a hose.
Metered and Unmetered Water
If your water is metered, every saving shows on the bill, and many companies charge for waste water based on the water supplied too. The price per cubic metre on your bill may be split into water and sewerage; add them together for the full price. Unmetered households pay a fixed charge, but saving hot water still cuts energy bills, because heating water is one of the biggest energy uses in a home.
Hot Water and Energy
Much of a household's water use is hot water, from showers, baths, taps and some washing machines. Heating it takes a surprising amount of energy: warming the 64 litres of an 8 minute shower from 10 °C to 40 °C takes about 2.2 kWh. That makes shorter or lower-flow showers one of the few changes that cut both the water bill and the energy bill at the same time.
Understanding Your Result
Water a day is the household's total daily use.
Per person gives the daily use for each person.
In US gallons gives the total in US gallons.
Per month and year gives the volume in cubic metres.
Cost gives the monthly and yearly cost at your price.
Biggest use shows which activity uses the most water.
Breakdown lists each use in litres a day.
When Should You Use This Calculator?
Deciding whether a water meter would save money.
Understanding a high water bill.
Finding the biggest savings in your household.
Planning for a hosepipe ban or drought.
Teaching children where water goes.
Common Mistakes
Underestimating shower flow, especially with power showers.
Forgetting outdoor use in summer.
Ignoring leaks, which never switch off.
Using the water price without sewerage charges.
Counting one shower when the whole household showers daily.