By cleaning the tank regularly, the moving parts will keep functioning properly, resulting in longer product life. Pour 300ml Cassette Tank Cleaner in a rinsed out tank and fill it with at least 5L lukewarm water. Shake the tank several times back and forth then set it down and leave it for at least 24 hours. After emptying, your waste-holding tank will be as good as new. Allow the tank to dry by leaving the blade open. Using Thetford Cassette Tank Cleaner before you store your camper or caravan for longer periods gives you a fresh start at the beginning of a new camping/adventure season.