Water use efficiency (in cities): leakage

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Losses of water in the distribution network can reach high percentages of the volume introduced. The problems with leakage are not only related to the efficiency of the network but also to water quality (contamination of drinking water if the pressure in the distribution network is very low). Leakage reduction applies to both distribution and customer supply networks.

Leakage losses are still significant in many urban areas (Figure 5.20). Commonly, this is due to the poor condition of water mains. Germany has low leakage levels due to a combination of favourable soil conditions, treatment to reduce the aggressiveness of the water supplied, easy access to repair mains and a high level of mains replacement. In accession countries, losses are significant and large parts of the distribution networks are made from worn asbestos cement pipes. Maintenance of the existing infrastructure is also neglected in most countries. Network losses in Slovenia in 1985 and 1990 were 31.7 and 30.4% of total water urban supply, respectively, but increased to an average of 43.8% during the period 1994-98 (Figure 5.21). In Slovenia, reconstruction of the water supply network started in 1995 by changing asbestos pipes.

Progress is being made to reduce leakage losses in some countries. In England and Wales, an active programme of leakage reduction reduced network losses from 29 to 22% of the total distribution input between 1992/3 and 2000/1 (Figure 5.21). In Malta, leakage control policies have been introduced to reduce leakage rates by 55% from 1995 to 2001. However, in Spain average water losses in the distribution network increased from 20.0 to 21.4% between 1996 and 1999, with only four regions recording a reduction in water losses over this period.