|Key people||Sir Peter Mason KBE (Chairman);
Martin Baggs (CEO)
|Services||Water supply and sewage treatment services|
Thames Water Utilities Ltd, known as Thames Water, is the private utility company responsible for the public water supply and waste water treatment in large parts of Greater London, the Thames Valley, Surrey, Gloucestershire, Wiltshire, Kent, and some other areas of in the United Kingdom. Thames Water is the UK's largest water and wastewater services company, and supplies 2.5 gigalitres of drinking water per day, and treats 4 gigalitres of wastewater per day. Thames Water's customers comprise 27% of the UK population.
Thames Water is responsible for a range of water management infrastructure projects including: the Thames Water Ring Main around London; Europe's largest wastewater treatment works and the UK's first large-scale desalination plant. Infrastructure proposals by the company include the proposed £4.2 billion London Tideway Tunnels, and the proposed reservoir at Abingdon, Oxfordshire, which would be the largest enclosed or bunded reservoir in the UK.
Thames Water is regulated under the Water Industry Act 1991 and is owned by Kemble Water, a consortium formed in late 2006 by Australian-based Macquarie Group's European Infrastructure Funds specifically for the purpose of purchasing Thames Water. Other large shareholders in recent years include: BT Pension Scheme (13%), the Abu Dhabi Investment Authority (9.9%)  and the China Investment Corporation (9%).
Thames Water can trace its history back to numerous earlier companies and individuals stretching back to the early 17th century:
1600s, 1610s Edmund Colthurst, Hugh Myddelton and later Sir John Backhouse were the driving forces behind the New River Company and the New River, which routed water from Hertfordshire to New River Head in Islington, and provided an additional source of drinking water to London. 1850s Joseph Bazalgette's remediation of The Great Stink provided the company with much of London's present Victorian sewerage infrastructure and several listed buildings within its portfolio of sites. Also in the 1850s, Dr John Snow's identification of the 1854 Broad Street cholera outbreak provided a stimulus to the better treatment of sewage. The Thames Conservancy was established in 1857 with unified control over water supply, drainage and navigation. 1973 The Thames Water Authority was founded, under the terms of the Water Act 1973, and took over the following water supply utilities and catchment area management bodies:
- Cotswold Water Board
- Croydon Corporation
- Epsom and Ewell Corporation
- The Lee Conservancy
- Metropolitan Water Board, responsible for water supply in London.
- Mid Southern Water Company
- Middle Thames Water Board
- Oxfordshire and District Water Board
- South West Suburban Water Company
- Swindon Corporation
- Thames Conservancy, responsible for managing the non-tidal River Thames (powers taken until 1989).
- Thames Valley Water Board
- Watford Corporation
- West Surrey Water Board
1989 Thames Water was privatised as Thames Water Utilities Limited, entailing the transfer of navigation, regulatory, river and channels management to the National Rivers Authority that later became part of the Environment Agency. The company became listed on the London Stock Exchange and was a constituent of the FTSE 100 Index. 2001 Thames Water plc was acquired by the German utility company RWE. As well as its British operations, it became an international water treatment consultancy and acquired some overseas operations. 2006 On 17 October 2006, following several years of criticism about failed leakage targets in the UK, RWE announced it would sell Thames Water for £8 billion to Kemble Water, a consortium led by the Australian Macquarie Group. In December 2006, the sale of the Thames Water's British operation went ahead, with RWE keeping the overseas operations. 2007 Under the new ownership, the company re-focused its efforts on improving its operational performance and announced the largest-ever capital investment programme (£1 billion p.a.) of any UK water company. 2012 Some of the company's stock was acquired by the BT Pension Scheme, the Abu Dhabi Investment Authority and the China Investment Corporation.
Every day, Thames Water supplies 2.5 gigalitres (2.5×109 litres) of potable tap water from 102 water treatment works via 288 clean water pumping stations through 32,000 km (20,000 mi) of managed water mains to 9 million customers (3.6 million properties) across London and the Thames Valley. It maintains 30 raw water reservoirs and 235 underground service reservoirs.
Likewise, it daily removes and treats 4 gigalitres (4.0×109 litres) of wastewater from 14 million customers (5.1 million properties) using 2530 sewage pumping stations through 109,000 km (68,000 mi) of managed sewerage mains to 350 sewage treatment works across an area of South England. On 1 October 2011, it adopted 40,000 kilometres (25,000 mi) - an additional 60% - of private sewers and lateral drains to add to its then stock of 69,000 kilometres (43,000 mi) giving the current total of 109,000 kilometres (68,000 mi) managed sewerage mains. Before 1 October 2016, it is obliged to adopt 5,000+ private sewage pumping stations to add to its current stock of 2530 managed sewage pumping stations 
As of 2013[update], it recovered approximately 18 MW (156 GWh per annum), or 12.5% of its total energy requirements from renewable electricity generated from biogas collected from the sewage. Further biogas capacity, the burning of 'fatbergs' removed from London's sewers and substantial solar farms have enabled the company to announce a 2015/2016 target of generating 36MW (318 GWh per annum), or 20% of its total energy requirements from renewable sources.
- Up to 2006 (RWE's ownership)
Thames Water was repeatedly criticised for the amount of water that leaked from its pipes by the industry regulator Ofwat and was fined for this.
In May 2006 the leakage was nearly 900 megalitres per day (Ml/day) and in June that year Thames Water missed its target for leakage reduction for the third year in a row. Also in June 2006 the firm announced a 31% rise in pre-tax profits to £346.5m. The Consumer Council for Water, a customers' group, accused Thames Water for continuing to miss their targets for the past five years. In July 2006, instead of a fine which would have gone "to the exchequer", the company was required to spend an extra £150 million on repairs.
- Since 2007 (Kemble's ownership)
Thames Water has hit its Ofwat-agreed annual leakage-reduction target for the past seven years running (2006 to 2013).
In 2006-07, the company stated that it had reduced its daily loss through leaks by 120 Ml/day to an average of 695 Ml/day. For 2009-10 Ofwat-reported leakage was 668.9 Ml/day. In its price control determination for the period 2010 to 2015, Ofwat did not allow the funds needed to finance a significant further reduction in leakage and used the assumption that leakage would be 674 Ml/day in 2010-11 and 673 Ml/day from 2011-12. The target for 2011-12 was surpassed by more than 30 Ml/day. In 2012-13, actual leakage was relatively unchanged at 646 Ml/day.
The company has achieved these reductions by
- better pressure management of known problem sectors of its older water network
- replacing 2,200 km (1,400 mi) of worn-out Victorian pipes, mainly under London
The recent successes in meeting leakage targets have mitigated the earlier failures to meet targets. As a result, Thames Water now leaks slightly less water than at privatisation in 1989, having reduced leakage from its 32,000 km (20,000 mi) network of water pipes to its lowest-ever level, down more than a third since its peak in 2004. As of 2013[update] and with an older network profile, Thames Water leaks 26%  of supply, slightly less than Severn Trent at 27%.
In the period 2005-2013 Thames Water was the most heavily fined water company in the UK for pollution incidents, paying £842,500 for 87 events. It also paid the largest fine for a single incident of £204,000. Following concern that the level of environmental pollution fines was too low, in 2013 the Sentencing Council proposed a significant increase in the level of fines. The proposals would see the average fine increase to £250,000 and the maximum £2 million.
The Thames Tideway
Joseph Bazalgette's remediation of the 1850s Great Stink renewed much of London's sewerage mains infrastructure. However, the new design was not intended to cope with the doubling of London's population over the following 150 years. The concreting of huge amounts of London's green spaces causes substantial rainwater run-off into the drainage and sewerage systems which had been expected to soak into the ground. As a result, even small amounts of rainfall in certain circumstances can cause London's outdated Victorian sewerage system to fail over, and release untreated sewage mixed with rainwater directly into the Thames Tideway.
Each year, on average, there are 50-60 such incidents and a total of 39,000,000 m3 (3.9×1010 l), or 39 million tonnes, is released.
The released effluent follows the ebb and flow of the tidal Thames, and can take up to 3 days to exit the Tideway into the Estuary. For this reason, Thames Water advises against swimming in the Thames Tideway.
The first two stages of the London Tideway Improvements are upgrades to 5 sewage treatment works and construction of the Lee Tunnel, due for completion in 2014. Together, these should result in an annual discharge reduction of 40%, or by 16 million tonnes to about 23 million tonnes per year. The third stage is the Thames Tideway Tunnel, which has been proposed by the Thames Tideway Strategic Study, including Thames Water, as an effective solution to deal with most of the remaining problem. Alternative proposals by other parties exist. The necessity for action has added urgency because of imminent water quality fines of up to £1bn on the UK Government by the European Commission.
In September 2007, 5 km (3.1 mi) of the River Wandle, Greater London was polluted. In January 2009, Thames Water pleaded guilty and was "fined £125,000 and ordered to pay £21,335 in clean-up and investigation costs". In February 2010, on appeal, the fine was found to be "manifestly excessive" and was reduced to £50,000.
On 29 October 2011, Thames Water released thousands of tonnes of raw sewage into the River Crane, Greater London killing thousands of fish, when a six-tonne valve jammed during routine maintenance. Despite tankering and alternative routing, the volume of sewage from Heathrow overwhelmed the operations. Thames Anglers Conservancy's Robin Vernon said: “It will take a decade to repair all the damage done by the sewage spill. Everything in there is just dead now.” In 2013, fungus and slime in the River Crane was attributed to run-off of de-icer from Heathrow getting into the river 
In 2011, the company found itself involved in a controversial redevelopment plan for the Bath Road Reservoir in its home town of Reading. An appeal against Reading Borough Council's rejection of the plan was dismissed by the planning inspector in January 2011. Full planning permission has since been granted on 10 December 2012.
- Rankin, Jennifer (10 June 2013). "Thames Water pays no corporation tax on £1.8bn turnover". The Guardian (London).
- "Annual Performance Report 2012-2013" (PDF). Thames Water. June 2013. Retrieved 16 June 2013.
- "Bye-bye big stink" (PDF). Beckton in Focus, The Newham Mag, London Borough of Newham. April 2010. Retrieved 9 March 2013.
- "Thames Water Desalination Plant, Beckton". Water-technology.net. Retrieved 2 September 2012.
- "Thames Tideway Tunnel". London Councils website. Retrieved 9 March 2013.
- "Need for reservoir 'not proven'". BBC News. 5 January 2007. Retrieved 12 February 2011.
- Ben Harrington (30 May 2012). "BT Pension Scheme seals deal for 13pc stake in Thames Water". London: The Telegraph. Retrieved 23 March 2013.
- "Macquarie sells 9.9% stake in Thames Water to Abu Dhabi Investment Authority". Waterbriefing.org. 13 December 2011. Retrieved 23 March 2013.
- "China wealth fund buys nearly 9% of Thames Water". BBC News. 20 January 2012. Retrieved 9 March 2013.
- The Thames Water Authority Constitution Order 1973
- Larry Elliott and Jill Treanor (22 November 2000). "A whole world sold on sell-offs". London: The Guardian. Retrieved 9 March 2013.
- Christopher Hope (19 February 2002). "Germany's RWE in frame for Thames Water owner Takeover bid for power giant sparks surge in share price". The Herald, Scotland. Retrieved 9 March 2013.
- "Thames Water to be sold for £8bn". BBC News. 16 October 2006. Retrieved 12 August 2013.
- Edmund Conway and Ben Harrington (17 October 2006). "Macquarie buys Thames Water in £8bn deal". London: The Telegraph. Retrieved 9 March 2013.
- "Thames Water in £1bn leaks plan". BBC News. 29 June 2007. Retrieved 9 March 2013.
- Duncan Mackay (31 May 2011). "London 2012 sign up Thames Water as sponsor". insidethegames.biz. Retrieved 9 March 2013.
- "GIS Foundation at Thames Water". Barnsnape Consulting. 2008. Retrieved 2 September 2012.
- "Thames Water Utilities Limited: Annual Report & Financial Statements for the Period ended 31 March 2012" (PDF). Thames Water. 26 June 2012. Retrieved 2 June 2013.
- "Thames Water and 2OC in £200m deal to turn ‘fatbergs’ into energy". waterbriefing.org. 8 April 2013. Retrieved 2 June 2013.
- "Thames Water to generate 20 per cent of energy needs with sewage scheme". utilityweek.co.uk. 5 March 2013. Retrieved 2 June 2013.
- "Thames Water misses leak target". BBC News. 22 June 2006. Retrieved 9 March 2013.
- "Thames Water escapes leakage fine". BBC News. 4 July 2006. Retrieved 9 March 2013.
- "Thames Water hails leak progress". BBC News. 26 November 2007. Retrieved 12 February 2011.
- "Service and delivery – performance of the water companies in England and Wales 2009-10 - Supporting information" (PDF). Ofwat. 27 October 2010. p. 46. Retrieved 12 February 2011.
- "Future water and sewerage charges 2010-15: Final determinations" (PDF). Ofwat. 26 November 2010. pp. 50–52. Retrieved 12 February 2011.
- "Thames Water leakage - explanatory graphs" (PDF). Ofwat. Retrieved 9 March 2013.
- 2012/13 figures: 643Ml/d of leakage; 2.5Gl/d of supply
- Fred Pearce (8 May 2012). "The water industry is burying a leaking pipes scandal". The Guardian (London). Retrieved 9 March 2013.
- "Revealed: how UK water companies are polluting Britain's rivers and beaches". The Guardian. 3 August 2013.
- "Environmental Offences Guideline consultation" (PDF). Sentencing Council. March 2013. Retrieved 25 Nov 2013.
- "Thames Tunnel Consultation". Thames Tunnel partnership. Retrieved 9 March 2013.
- "Thousands of River Thames fish killed by storm sewage". BBC News. 8 June 2011. Retrieved 2 September 2012.
- "Thames Water warns David Walliams against swimming into London". New Civil Engineer (nce.co.uk). 12 September 2011. Retrieved 22 June 2013.
- Luke Cross (13 November 2012). "Open Doors: Lee Tunnel lifts lid on 'exciting' world of construction". Construction News. Retrieved 9 March 2013.
- "UK faces fine on EU water breach". BBC News. 18 October 2012. Retrieved 8 June 2013.
- Fiona Harvey (26 January 2012). "Thames super-sewer a 'necessity' to prevent EU fines". London: The Guardian. Retrieved 8 June 2013.
- Britain’s largest water company prosecuted for 5km river pollution, Environment Agency, February 2009; retrieved on 5 February 2009.
- "Thames Water fine for toxic spill in River Wandle cut". BBC News. 15 February 2010. Retrieved 9 March 2013.
- "Thames Water ordered to pay £14K+ for stream pollution". waterbriefing.org. 25 February 2013. Retrieved 9 March 2013.
- Rachel Bishop (1 November 2011). "River Crane 'destroyed' by sewage spill". Richmond and Twickenham Times. Retrieved 2 September 2012.
- Robert Cumber (21 March 2013). "Heathrow blamed for slime pollution in river". Hounslow Chronicle. Retrieved 27 March 2013.
- "Thames Water forced to pay out £60,000 over sewage spill". Reading Post. 9 December 2011. Retrieved 2 September 2012.
- "Bath Road reservoir homes appeal rejected after inquiry". BBC News. 15 January 2011. Retrieved 9 May 2011.
- "Consultation on Construction of Homes at Bath Road Reservoir Site". Reading Borough Council. 7 February 2013. Retrieved 23 March 2013.