The southern route runs 3.1 miles from Honor Oak, one of our underground reservoirs, to Brixton.

It will allow up to 200 million litres of water per day to be transferred from the Thames Water Ring Main at Brixton to Honor Oak Reservoir.

Prior to tunnelling, ground investigations were conducted using boreholes, to identify the ground conditions.

Further studies were undertaken to confirm the location of underground services and the presence of deep foundations. Using this information we determined the final routes of the tunnels.

The tunnel is 4,850 metres long and approximately 45 metres below the surface, well below the depth of any service pipes or cables and the London Underground.

The tunnel will be lined with steel and concrete and connected to the Ring Main ready for service in March 2010.

We have completed the work we started in June 2007 and are now in the final stages of commissioning.