Report No DWI0635

Sept 1984

1.1 This report summarises a joint programme of work at central and local government level which was set in train to resolve speculation about the apparently high unit domestic consumption of water in Scotland. It draws together the main features of three aspects of the study: levels of consumption, the nature of consumption and methods of consumption measurement.

1.2 As a result of the work which has been undertaken, the historic concept of particularly high usage in Scotland has been disproved and no evidence was found of significant variation between Scottish regions.

1.3 In addition the studies have provided, for the first time in Scotland, a picture of patterns of water use by different sections of the community in terms of their ownership and frequency of use of the major water-using appliances in the home.

1.4 Aside from the basic purpose of the study it was found necessary to carry out a substantial programme of meter assessment as part of the process of validating the water quantity measurements. As part of this supporting work an effective method for in situ calibration of meters was developed and this also is discussed.

1.5 As part of the need to look forward in terms of water resources planning some attempts are made to assess the main components of domestic water use and the implications for these of changes in market penetration and pattern of use of domestic water appliances.

1.6 Principal Conclusions

1. A median figure for domestic consumption of water at 32 locations in Scotland has been determined as 119 litres per head per day.
2. The components of use, and the frequency and pattern of use, are broadly similar to those found by English authorities.
3. Use of water has been found to depend substantially on household characteristics but not upon geographical location or type of housing or pressure of supply.
4. Standard water meters do not comply reliably with the manufacturer's specification.
5. In-situ calibration provides a practical and practicable method for assessing the performance of small water meters under service conditions. The technique enables corrections to be made for zero shifts and permits waste meters to be used to provide tolerably good data on flow volumes.
6. For planning purposes it is recommended that current estimates of consumption should be based on 120 ± 15 litres per head per day. These rounded figures correspond approximately to the median and quartile values derived from this study and may be applied generally. In planning ahead regard should be paid to likely movements in the components of water use and the market penetration of optional water using appliances when assessing charges in the median value of per capita consumption.

Copies of this report may be available as an Acrobat pdf download under the 'Find Completed Research' heading on the DWI website.