The Mayor's draft water strategy - london.gov.uk - Greater London ...

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there is or could be a serious shortage of water for it to distribute to its customers. When hosepipe bans were last introduced in the summer of 2007, there were complaints (including many letters to the Mayor) that Table 2.6 Companies’ levels of service – water supply restrictions public gardens were still being watered and paving washed down. The government now proposes to widen the range of non-essential uses of water that can be controlled by water companies. This would Water Company Hosepipe ban Drought order/permit Rota cuts/standpipes Thames Once every 20 years Once every 20 years Never Veolia Water Three Valleys Once in 10 years Once in 20 years Unacceptable Essex & Suffolk Once in 20 years Once in 50 years Never Sutton & East Surrey Once in 10 years Once in 20 years Once in 100 years Table 2.7 Water supply statistics for London (2008/09) Population served (000) (London per cent of company total) Overall water supplied (million litres per day) (London per cent of company total) Thames Three Valleys 6,090 (71.1%) 1,870 (72.7%) 1,015 (32.5%) 281 (34.1%) Essex & Suffolk 532 (29.8%) 136 (30.1%) Sutton & East Surrey Total 289 (44.7%) 7,927 67 (43.5%) 2,354 Proportion of London’s water distributed by company 79.5% 11.9% 5.8% 2.8% 100% Household water consumption (litres/person/day) 160 173 160 161 162 Proportion of households with water meters in London 21.2% 33.5% 42.7% 28.2% 24.5% Distribution loss (million litres per day) 378 35 14 7 435 Percentage loss 20.2% 12.4% 10.6% 10.1% 18.5% (London per cent of company total) (75.0%) (39.1%) (32.5%) (44.3%) Total leakage (million litres per day) 527 52 22 11 611 Percentage loss 28.2% 18.5% 15.9% 16.4% 26.0% (London per cent of company total) (75.1%) (36.8%) (32.4%) (44.7%) Leakage per property (litres per day) 207 127 94 88 185 Security of supply index 2008/09 56 100 84 100 Security of supply index 2007/08 89 100 100 82 Security of supply index 2006/07 60 100 100 97 The figures in brackets show the London proportion the company-wide totals. Security of supply index is a measure of each company’s ability to supply customers in dry years without imposing demand restrictions such as hosepipe bans. 100 is the highest index score. The index relates to the whole company. Source: Water companies’ June Returns to Ofwat 33
34 The Mayor’s draft water strategy increase the ability of water companies to manage demand in times of water shortage, particularly in the early stages of a drought or where supplies of water available for distribution deteriorate rapidly 2.18 Domestic uses that might be prohibited as a result of these changes include, for example, the cleaning of patios with a hosepipe or pressure washer and the filling of domestic swimming pools. The government also wants to allow the water companies to use their powers to ban or restrict nonessential uses of water more flexibly. The government is currently seeking views on these changes through its consultation on the Draft Flood and Water Management Bill 16 . 2.19 In general the Mayor supports these proposals but they need to apply to public areas as much as domestic use if they are to gain the support of the general public. 2.20 Water companies divide their supply area into ‘water resource zones’ (WRZ) that are defined on the basis of good water supply connectivity. Customers in each zone experience the same risk of water restrictions. There are six zones covering London, which also supply water outside London. The current dry year annual average situation for these zones is: • Sutton & East Surrey Water - East Surrey WRZ: Critical peak deficit until 2011/12. No dry year annual average deficit - Sutton WRZ: No deficit • Essex & Suffolk Water - Essex WRZ: Deficit until 2013/14 • Thames Water - London WRZ: No deficit (assuming the desalination plant is online – see paragraphs 2.21 and 2.31) • Three Valley Water - Southern WRZ: No deficit - Central WRZ: No deficit 2.21 In a dry year, Thames Water currently forecasts that its demand for water in its London resource zone would be about 80 million litres per day (Ml/d) greater than its available supply. This is equivalent to about half million people’s daily demand, but it is a significant improvement on the previous forecast of 170 Ml/d. This has largely been achieved as a result of the Victorian Mains Replacement Programme (see paragraph 3.8) and other action to reduce leakage. Even so, large parts of London’s water supply network date back to the Victorian period, with over 60 per cent of the network built pre-1900. It is this aged infrastructure that leads to most parts of London having the highest levels of mains leakage in England and Wales. The desalination plant at Beckton (see paragraph 2.31) that is undergoing its final commissioning will close this deficit. 2.22 The security of supply index is an indicator of the extent to which the company is able to guarantee provision of its planned levels of service. A company showing a supplydemand deficit (or in other words having a security of supply index of less than 100) means that its customers face a higher risk
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