Tube Lines upgrades and maintains the London Underground's Jubilee, Northern and Piccadilly lines. It employs more than 3,300 staff and in 2008 turned over £874m.
The company's environmental policy has 'more sustainable use of resources' as a major goal, and better management of water has been a key focus in the past few years.
The Green Business Awards judges were particularly impressed by Tube Lines' installation of rainwater harvesting to supply water for train-washing at its Cockfosters depot, cutting the consumption of purified mains water. This was the first application of rainwater harvesting on a major transport site in the UK, according to Tube Lines, which saw benefits not only in reduced mains water consumption but also in a lower carbon footprint. It's now looking at implementing a similar scheme at a separate depot.
At another facility in Golders Green, there was no space to store water gathered from roofs, so Tube Lines installed a green roof - another first for London Underground buildings. This structure regulates water flow, helping to protect the drainage system against leaks and flooding.
Tube Lines has also taken a series of steps to reduce water use at its two main corporate sites, which account for the bulk of its water consumption. 'Hippos' have been placed in all toilet cisterns, reducing the amount of water used by one litre per flush. The timers on urinal washes have been modified. Kitchen practices have been improved.
Water use is closely monitored and reported, and staff have been engaged in the drive for greater water efficiency - for example, by in-house events and through coverage in the company magazine and on weekly staff e-mails.
The company has reported a dramatic drop in water use at its corporate sites since the technical and staff awareness measures were introduced. Absolute water use was cut by 75% between 2006 and 2008, hitting a target set for 2009 one year early.