Hot Water

Page last updated at 15 June 2015 at 14:57

Hot Water  Cylinder20jacket M

18% of domestic energy is used to heat our hot water and a lot of the heat is lost through poorly insulated hot water cylinders and pipework. So regardless of the method you use to heat it there is always a certain amount lost. 

Check the lagging on the pipes (particularly if they travel through the cold loft) and the insulation jacket around the cylinder if you have one. These can be added very cheaply on a DIY basis. 

But not all properties have a cylinder, some have hot water on demand and both have different things to consider when using them at their most efficient: 

A tank ...

Re-acquaint yourself with your hot water timer and heat the water when you need it rather than when you don't. Have the hot water ready in the morning and evening. You may find you can get through the day without any further heating if your tank is properly insulated. Running your water heating system all day may not be the most efficient way of heating your water. 

If you have to use an emersion heater take care not to leave it on. It is an expensive way to heat your hot water. 

or no tank

Many properties have been fitted with a hot water on demand system, most often with a combination boiler. In general these systems are more efficient than a tank system because you only heat the water you need. But some hold a small internal reservoir of hot water which is kept up to temperature so may not be as efficient as expected. 

Use less hot water

The best way to save money on your hot water is to use less of it. Depending on how far away your taps are from the tank or boiler you may end up wasting a lot of cold water before the warm water gets through. Mixer taps are especially bad at this because they are often set to a warm setting without even checking. You end up washing your hands in cold water and warming some of the pipes. 

Baths v Showers

Most showers use considerably less water than baths and are therefore more efficient. An average 8 minute shower uses 62 litres and some power showers can use up to 136 litres compared with an average bath's 80 litres. Installing a water saving shower head will drop usage to just 32 litres. 

In general, baths use a lot more water than a normal shower but here are a few tips to consider:

  • Don't fill the bath too much
  • Share the bath water
  • Install a water efficient shower head
  • reduce the length of your shower 


Most washing machines run on just cold water these days but some still have a hot water intake which if too far away from your tank or boiler may not ever receive hot water. These machines still work but end up heating the water internally. Instead of drawing hot water you can get a fitting to fill both hot and cold intakes with cold water. 

When buying a new washing machine ensure it has cold water intake only because it will only heat the water it needs. 

Other Links

Visit Southern Water's pages on water saving tips for help on reducing water usage in the home and garden. 

Try the Energy Saving Trust's Water Energy Calculator. Gives you an indication of the amount of water you use and energy required to heat it. Then adjusting your findings will help you work out how to reduce water usage. 

To find out about planning issues relating to water, visit our planning advice pages.


To find out more, contact Giles Gooding on 023 8068 8274, email, Twitter @EcoEastleigh