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

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demand and supply in the short term. In closing its gap, Thames Water aims to reduce its overall leakage rate from 894 million litres of water a day in 2005/06 to 685 million in 2009/10. At the same time, Thames Water is constructing a new water treatment plant at Beckton as a means of rapidly reducing its security of supply deficit. The plant would enable Thames Water to take water from the Thames Estuary and remove the salt from it. The plant will only operate when demand cannot be met from conventional water sources. At full operation, the plant could supply 140 million litres of water a day; enough water to supply 400,000 homes. 2.32 A biodiesel-fuelled electricity generation plant is being built to offset the carbon dioxide emissions. The plant is designed to operate ‘24/7’ and the output will normally be used to power the standard sewage treatment processes at Beckton, with a small amount going to the desalination plant to keep it in a state of ‘preparedness’. The generation plant will, over time, balance the power requirement of the desalination plant but it will not be able to meet the peak power demand of 18 megawatts on the occasions that it is in full operation. A new reservoir 2.33 Some major new resource developments, for example a reservoir, can take in excess of 20 years from conception through to implementation. Thames Water believes that it will need a major new source of water to meet the forecast demand by 2026. Its preferred option is a new storage reservoir in the Upper Thames area, outside of London. Pumping water from the river Thames at times of high river flows would fill the new reservoir 20 . The reservoir, which is referred to by Thames Water as the Upper Thames Reservoir, has been included in the company’s draft Water Resource Management Plan 21 . However, the Environment Agency said in its response to the draft plan that it is yet to be satisfied that the proposed reservoir is the best solution for the company’s customers, the environment and the wider South East 22 . In its Statement of Response to the public consultation, Thames Water has said that the scheme would be delayed up to five years and may be reduced in size from 150 million cubic metres (Mm 3 ) to 100 Mm 3 . As noted in paragraph 2.13 above the Secretary of State has now called for an inquiry into Thames Water’s draft Water Resource Management Plan. 2.34 The group opposed to the reservoir has proposed alternatives, including water transfer from the River Severn to the River Thames and effluent reuse (see below). The feasibility of Severn-Thames transfer was studied by the former National Rivers Authority in the early 1990s and at that time it was considered to be a cost-effective option for increasing water resources 23 . However, it has not been supported by more recent Environment Agency studies 24 or considered feasible by Thames Water. Wastewater effluent reuse 2.35 It is clear from what has been said above that there is little scope for developing new 37
38 The Mayor’s draft water strategy sources of river water or groundwater in and around London. However, reclaiming wastewater (referred to as ‘effluent reuse’) from sewage treatment works is a significant potential new resource that Thames Water and other companies are currently investigating. It would be a dependable source but it may have an ‘image’ problem. Ensuring drinking water integrity, understanding customer attitude, and minimising the increased energy consumption are the key associated issues. 2.36 What Thames Water is investigating is indirect reuse, which is where the reclaimed water would be returned to a watercourse and then abstracted into storage to blend with other water before treatment and supply. This provides an important buffer between the effluent discharge and the water supply customer and mirrors what happens elsewhere in the catchment. However, the catchment areas of the London works are heavily urbanized with significant proportions of industrial effluents. This is in marked contrast to the Langford Scheme in Essex where the effluent is derived from domestic customers. Thames Water believes that it is right to complete its research into the process requirements and risk assessments before accepting that such a scheme would be feasible. The effects of climate change 2.37 In the longer term, water resources will be affected by changes in our climate. The UK Climate Impacts Programme have reported that the UK is getting warmer by 0.4 – 0.9˚C since 1914, whilst witnessing eight of the ten warmest years on record since 1990. A separate analysis of London’s climate record has identified that summer temperatures in London have risen at an average rate of 0.73˚C per decade over the last 30 years 25 .
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