SOUTH West Water is again giving its customers the chance to discover the hidden secrets of the region's largest reservoir.

The company is offering free guided tours of Roadford Dam on Thursday, September 12 as part of this year's national Heritage Open Days programme.

Roadford Lake was opened in 1990 as the centre-piece of a programme to almost double the region's water storage capacity following the drought of 1976.

After walking through the dam, which impounds water from the River Wolf to form a reservoir with a net storage of 34,500 megalitres, visitors will scale 170 steps to the top of the valve tower.

The steep climb is not for the faint-hearted and is physically demanding but offers a unique opportunity to view this spectacular lake.

South West Water's head of drinking water services Guy Doble said: 'Roadford has played an important role in supplying clean water to large parts of the region for more than 20 years.

'We are looking forward to welcoming visitors to see for themselves how we manage this key water source.'

Places on the free tours are limited and must be pre-booked. Tours run between 10am and 4pm and last for an hour.

To book a place, contact South West Water on 01392 443766 (Monday to Friday, 9am to 5pm).

Places on Friday, September 13 are already fully booked.