Carbon Dioxide Emission Savings Potential of Household Water Use Reduction in the UK

The relationship between household water use and energy consumption was examined to establish whether the conservation of water within a domestic environment offers significant potential for saving energy, thereby reducing household carbon dioxide emissions. Average UK water usage is 55,121 L ca -1 yr -1 . The supply of this volume of water and its subsequent treatment by the water companies is equivalent to just 38.6 kg CO 2 ca -1 yr -1 , although this is not currently included in the primary footprint. So water consumption per se does not significantly effect CO 2 emissions. However, the heating water within the household using electricity requires 5,036 kWh ca -1 yr -1 , equivalent to a further 2,830 t CO 2 ca -1 yr -1 with 57% of energy associated with use of heated tap water. Using gas instead of electricity to heat water can reduce emissions by 63%, equivalent to an average reduction of 4.36 t CO 2 yr -1 for a standard household (2.4 occupants). Water efficient appliances and the careful use of heated water in the home could reduce average household water use from 151 to 73 L ca -1 d -1 as well as the volume of water required to be heated thereby reducing related emissions by 58% or 1,662 kg CO 2 ca -1 yr -1 , where electricity is used. Maximum CO 2 emission reduction is achieved by the use of solar collectors using gas as standby heating fuel. This, coupled with simple water conservation measures, emits as little as 130 kg CO 2 ca -1 yr -1 a potential saving of 2.7 t CO 2 ca -1 yr -1 .