Jersey Water will be opening their doors to the public this Saturday for an exclusive look inside the Queen's Valley Reservoir.
The tour, which is raising money for Mind Jersey, will include a look around the Dam, Draw-Off Tower and Pumping Station.
Organisers hope it will offer islanders a 'unique' insight into how Jersey's water tunnels work.
People will also learn the details of how it was built, how it holds 1,193 megalitres of raw water, the inner workings of the Pumping Station and Draw-Off Tower and how the water eventually ends up in people's taps.
Tours will be conducted by engineers at Jersey Water and will last approximately 30 minutes. It starts at 11am through to 4pm.
All proceeds will go to Jersey Water's Chosen Charity for this year, Mind Jersey. The water company say for every £5 raised, they will match it.
- WATCH: Our reporter Susan Ripoll gets a sneak peak of the tunnels below the dam.
More information on the Queen's Valley charity open day here.