International Comparisons of Domestic per Capita Consumption (2008)

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This work by the Environment Agency presents a review of methods used to estimate domestic per capita consumption (PCC) of water. It focuses on countries with lower average PCC than England and Wales while having similar climates and economies. The reported PCC values were analysed based on several parameters including metering and water charges. The review indicates major differences between the water sectors in the reviewed countries and in England and Wales, particularly in what regards the extent of metering and scale of demand management measures. Water companies in England and Wales are recommended to adopt the ‘twin track approach’, reducing demand as well as increasing supply when developing their WRMPs.

Executive summary

This work presents a review of methods used to estimate domestic per capita consumption (PCC) of water in selected countries. It focuses on countries that are reported to have lower average PCC than England and Wales. Northern and western European countries that have climates and economies similar to England and Wales have been selected to provide meaningful comparisons. These include Austria, Belgium, Denmark, Finland, Germany and the Netherlands. The reported PCC values have been analysed in terms of:

  • ▼  Metering
  • ▼  Average household size or occupancy
  • ▼  Inclusion/exclusion of supply-pipe leakage in the estimated PCC
  • ▼  Water charges
  • ▼  Any demand management measures that may have played a part in the reported PCCThe review indicates that the major differences between the water sectors in the countries reviewed and in England and Wales are the extent of metering and scale of demand management measures. All of the countries reviewed have universal metering, although in most cases flats are not individually metered. There have been prominent demand management drives in Copenhagen and Hamburg since the 1980s. All of the countries reviewed, with the possible exception of Austria, have run national water conservation schemes. Water charges are based on the cost-recovery principle, except in Austria, and in most cases are higher than in England and Wales. Profit making is not always allowed, and in Belgium, the water charging system has a strong social element. In terms of components of domestic use, toilet flushing in England and Wales stands out, using between 13 and 21 more litres per head per day (l/h/d) than in the countries reviewed. This suggests that many toilets in England and Wales have high-volume cisterns. Direct comparisons of ownership and frequency of use of appliances could only be made with the Netherlands. There are no significant differences in ownership of water-efficient appliances, which suggests that the differences in consumption mainly result from differences in frequency of use.In view of the above, universal metering stands out as a key area for England and Wales. Water companies in England and Wales, particularly those in the water stressed South East of England, have considered universal metering in their draft Water Resource Management Plans (WRMPs) covering the period up to 2035. Metering can potentially reduce consumption by between ten and 15 per cent which will significantly reduce PCC. However, metering alone will not be enough to lower PCC to the desired level and additional measures, such as fitting older cisterns with variable flush mechanisms, will need to be considered.When developing their WRMPs, all water companies in England and Wales should adopt the ‘twin track approach’ to consider the full range of options available for reducing demand as well as increasing supply. However, in most cases demand management focuses on metering and reducing leakage. Traditionally water resources plans have focussed on resource development due to perceived uncertainty around the potential savings of demand management. This is perhaps the area where strategies need to be re- considered.Comprehensive demand management strategies, which involve not only metering and leakage reduction, but also high-profile water efficiency programmes aimed at changing behaviour and attitudes towards water use, are in place in countries around the world. National or regional water efficiency strategies with mandatory targets that take into account relevant demographic and socio-economic factors could help to reduce average PCC in England and Wales.

Further research should focus on obtaining more detailed information from one or two selected countries for a thorough analysis of the methods used to calculate PCC. Good quality data is available for the Netherlands which has ten water suppliers, so it is a possible candidate for such an analysis. It is also important to understand the differences in PCC reported by the water companies in England and Wales.

A broad consensus on the likely nature of future trends in domestic water use will help in developing consistent demand management strategies to be implemented regionally or nationally rather than by water companies.