Skills school Keeping an onboard water tank fresh
Some luxury caravans are fitted with an onboard water tank, which needs to be filled with clean water. Depending on the size of the van, these vary in capacity from around 40 litres upwards.
Most are filled from an external water-carrier, through a second port on the side of the caravan. Others are like some motorhomes, and can be filled with a hosepipe, through a filler cap located on the side of the vehicle.
To avoid stagnation, water should not be left in any tank for more than two or three days if it’s not being circulated, because there’s the potential for dangerous microbes to build up.
An onboard water tank should be drained down before you tow your caravan. Each litre of water in the tank weighs 1kg, so a full 40-litre tank will be the equivalent of a child passenger!
This will increase your fuel consumption and could affect handling, especially if the tank is located towards the rear of the caravan, where the ‘pendulum effect’ is most potent.
The procedure for emptying the water tank varies from caravan to caravan. Most vans drain down via a small inline valve, located close to the heating system.
A few tanks sit under a hatch in the floor. With these, you often find a handle and pull-cord, which opens a valve and drains the tank.
Other vehicles have an external drain tap, which sits underneath the edge of the caravan.
Draining the internal water tank is sufficient for towing, but for the purposes of winter storage, you should consider draining down the entire system.