The new arrangements include the opportunity to extend for a further five years into the next water industry regulatory regime period.
The contract includes a provision for looking after private drains and sewers after responsibility for them is transferred to the water companies in October 2011.
Enterprise group chief executive Neil Kirkby said: “This contract renewal is one of a number recently awarded to Enterprise by STW in AMP5. It reflects the hard work and customer commitment of our staff. We have worked in partnership with STW since 1998 and have made a significant contribution to the many operational improvements achieved by the joint teams.
“We look forward to working with STW over the next five years to drive lower costs, improve efficiency and improve levels of customer satisfaction, through the use of our bespoke IT systems and the strength of our presence in the Midlands area.”