Thames Water, Britain's biggest water and sewerage firm, has awarded a contract to Black & Veatch to carry out up to £100million of essential work to improve and maintain its sewage and water treatments plants in the Thames Valley region over the next five years.

This is the company's final "base load" contract of work to maintain its water pipes, sewers and other facilities across London and the Thames Valley in good order between April 2010 and March 2015. All of the contracts have a combined potential value of £1.3billion over the AMP5 investment period.

Martin Baggs, Thames Water's Chief Executive, said after finalising the agreement at the company's headquarters in Reading, Berkshire:

"We've challenged all our contractors to deliver the best possible value for our 13.6 million customers' money. Instead of letting lots of small contracts to multiple contractors, we're working with a select group of leading organisations to deliver the base load of our five-year investment programme.

"Our operational performance is better than ever right now - best-ever water quality, best-ever sewage works compliance and leakage down 24 per cent in the past four years. Our new approach will help us build on these standards of excellence over the next five years."

The following base load contracts were awarded at the start of April:

1. Optimise (J Murphy & Sons/Clancy Docwra/Barhale/MWH) for north London and Thames Valley water pipes and sewers;
2. MGJV (Morrison Utility Services/Galliford Try) for south London water pipes and sewers;
3. GBM (Galliford Try/Biwater/Mott MacDonald) for north and south London water and sewage treatment works.

The work in the contracts includes:

• continuing to replace London's worn-out Victorian water mains,
• upgrading sewers to protect customers' homes from sewer flooding,
• improving water and sewage treatment works,
• and extending water and sewerage networks to accommodate future population growth.