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Reports on water companies
International comparisons - network activity: results for 2006-07 Key conclusions
Table 15 show the activity rates and performance for both the water and sewerage networks. Network activity Portugal has the highest average water mains renewal rate, followed by England and Wales. The rates for Scotland and Canada are similar and within the England and Wales range. Portugal also has the highest average rate of sewer renovation or replacement, although the two Australian companies that reported this data have rates at the upper end of the Portuguese range. The sewer activity rate for Scotland is lower than England and Wales, although its activity on critical sewers is similar. A sewer is 'critical' where if it should fail, the subsequent costs would be significantly higher than if it had been rehabilitated before failure. The renewal rates for the USA are the percentage of expenditure on the asset divided by the asset value and are therefore not directly comparable with the other rates listed in the table. As a comparison, the water mains renewal rate in England and Wales for 2000-05 was 3% and 0.5% for sewers, based on the asset value in 2002-03. Network performance Canada and Portugal both report a lower average number of water mains bursts than England and Wales. Canada also reports a lower average number of sewer collapses than England and Wales. However, the average sewer collapse rate is higher in Portugal than in England and Wales. Differences in both soil type and the age of a network may contribute to relative performance. Higher values for water mains bursts in Australia reflect the current drought conditions. Movement in clay soils has caused pipes to crack and move out of alignment. It has also caused increased tree root invasion. Scotland and England and Wales have a similar water mains burst rate. This reflects significant investment by Scottish Water in its water mains and sewers during the Quality and Standards II programme (2002-06). However, Scotland's sewer collapse rate remains outside the range of the England and Wales companies because it includes lateral sewers. The highest values reported for both water mains bursts and sewer collapses are in the USA. The burst rate would be similar in England and Wales if we included repairs to valves, hydrants and service pipes in this measure. Likewise, if we included blockages with the number of sewer collapses in England and Wales, the USA rate again would be similar. The USA's Environment Protection Agency projects that $151 billion and $390 billion (£97 million and £252 million) respectively needs to be spent every year for the next 20 years to repair obsolete water and sewerage systems.  |
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Network activity |
Network activity - results for 2006-07
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