Water Saving Calculator for Mixer Showers (not Electric Showers)

The first step to saving water and energy is knowing exactly how much you are using. By purchasing a Water Flow Rate Testing Bag this will allow you to see the water consumption and be able to make in informed decisions about water and energy saving.

For example if you have a high flow 12L/min shower head (not unusual), you spend 10 minutes in the shower on average, once a day, 320 times a year, you will use £201 of water and gas PER person per year

You change to a 6L/min shower head, you reduce your time to 5 minutes in the shower, once a day, 320 times a year, you will use £52 of water and gas PER person per year

Please use the calculator below to show the possible water and gas savings you can achieve.

Shower Cost Savings Calculator (based on gas boiler and mixer shower)

Cost per litre for metered water* Pence
Cost per kwhr for gas (if you don’t kncow, use 5 pence) Pence
Current Usage (annual per person)
Current shower water flow (found using test bag) L / min
How long in the shower (minutes) min
Showers per day
Shower days per year
Water Consumption
L / person
Metered Water Cost£
Gas Consumption£
Current Total Cost - per person / year
New Shower Savings
New shower head flow rate L / min
Reduce your time in the shower to (minutes) min
Showers per day
Shower days per year
NEW Water Consumption
L / person
NEW Metered Water Cost£
NEW Gas Consumption (0.015 m3/min)**£
NEW Total Cost - per person / year

Total Saving - per person / year


*0.45p/L for metered water includes wastewater charge.  Utility companies assess the amount of wastewater based on the amount of metered water consumed, therefore if you spend longer in the shower, your wastewater charges also go up.  Some water companies offer lower pence/litre supply and wastewater charges for higher consumption rates. Combined water supply and wastewater charges can be a low as 0.30p/litre in some areas.

** 0.015m3/min gas consumption is based on a condensing boiler typically fitted within the last 10-15 years which almost always has a modulating gas burner.  You can tell if it is a condensing boiler if it has a condensate drainpipe beneath it.  This means, the condensing boiler turns down the gas flow depending on the amount of hot water being used.  Full flow hot water means high gas usage, but a low 6 or 8 litre per minute gas flow means less gas per minute used by the boiler.