|Area served||United Kingdom, but principally South England|
|Employees||4,700 staff, many contractors|
|Parent||Kemble Water Holdings Ltd|
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 the United Kingdom. Thames Water is the UK's largest water and wastewater services company, and supplies 2.6 gigalitres of drinking water per day, and treats 4.4 gigalitres of wastewater per day. Thames Water's 15 million 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 Holdings Ltd, 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 (8.7%). The name of the company reflects its role providing water to the drainage basin of the River Thames and not the source of its water, which is taken from a range of rivers and boreholes.
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 and William Farr'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 Responsibility for navigation, regulatory, river and channels management was transferred to the National Rivers Authority and later became part of the Environment Agency. The remainder of Thames Water Authority was privatised as Thames Water Utilities Limited. The company became listed on the London Stock Exchange and was a constituent of the FTSE 100 Index. 1995 Following international expansion, Thames Water became the world's third largest water company 2001 Thames Water plc was acquired by the German utility company RWE. As well as its British operations, it continued as an international water treatment consultancy and acquired further 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 Holdings Ltd, a consortium led by the Australian Macquarie Group. In December 2006, the sale of 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 2017 Under the Government's Open Water programme, and in common with all Water and Sewerage companies, Thames Water must provide entirely separate Retail and Wholesale operations for its commercial customers, working through a central Market Operator.
Every day, Thames Water abstracts / extracts, treats and supplies 2.6 gigalitres (2.6×109 litres) of potable tap water from 102 water treatment works via 288 clean water pumping stations through 31,100 km (19,300 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, treats and disposes 4.4 gigalitres (4.4×109 litres) of wastewater from 15 million customers (5.1 million properties) using 2530 sewage pumping stations through 108,000 km (67,000 mi) of managed sewerage mains to 350 sewage treatment works across an area of 13,000 km2 (5,000 sq mi) of South England. On 1 October 2011, it adopted 40,000 km (25,000 mi) - an additional 60% - of private sewers and lateral drains to add to its then stock of 68,000 km (42,000 mi) giving the current total of 108,000 km (67,000 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 
Thames Water produces biosolid fertiliser as a by-product from the waste treatment, and supplies this to local farms. It also recovers phosphates - an increasingly important source of a dwindling naturally-occurring mineral.
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 2015-16 target of generating 36MW (318 GWh per annum), or 20% of its total energy requirements from renewable sources.
Since 2007, it has made capital investments of c. £1 billion p.a. in its infrastructure - the largest such annual investment within the UK water industry. This level of investment has allowed the company to defer, but not avoid, substantial portions of its corporation tax liability in line with UK tax law.
- 2001-06 (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. 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.
- 2007-date (Kemble's ownership)
Thames Water has hit its Ofwat-agreed annual leakage-reduction target for the past eight years running (2006 to 2014).
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. In 2011-12, actual leakage was 637 Ml/day; in 2012-13, actual leakage was relatively unchanged at 646 Ml/day; in 2013-14, actual leakage was 644 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 31,100 km (19,300 mi) network of water pipes by more than a third since its 2004 peak to its current lowest-ever level. As of 2013[update] and with an older network profile, Thames Water leaked 25.8%  of supply, slightly less than Severn Trent at 27%. As of 2014[update] Thames Water leaks 24.7% of supply.
In the period 2005-13 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 in the water industry 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.
Conversely, in 2014, Thames Water admitted that it had accidentally over-reported the number of properties at high risk of sewage flooding between 2005-10. It agreed a compensation package for customers of £86m 
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. In 2013-14, exceptional weather conditions and flooding caused a total release of 55,000,000 m3 (5.5×1010 l), or 55 million tonnes. 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 and, by extension, walking in the tidal strand area.
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 2015. 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. On 12 September 2014, planning consent was formally approved by the UK Government.  The necessity for action has added urgency because of imminent water quality fines of up to £1bn by the European Commission on the UK Government.
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 2014, Thames Water blamed recent pollution on fat poured down drains by local customers
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.
The exceptional rain and weather conditions of 2013-14 caused swollen rivers and several low-lying Thames Water treatment works to be submerged under flood water.
In February 2014, the River Ash caused flooding in homes in Staines-upon-Thames. This flooding was exacerbated by a two-day delay by Surrey County Council's 'Gold Control' flood control group in ordering Thames Water to close a sluice gate on a Thames Water aqueduct. Thames Water considered it had been following an existing protocol agreed with Surrey County Council and the Environment Agency. 
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