Thetford Aqua Kem Blue Toilet Additive is a powerful fluid to clean out your waste holding tank. It liquefies waste to make it easy to empty the tank with as little mess and fuss as possible. It gives you great odour control, reduces gas build up, and a single dose lasts up to 5 days. Aqua Kem Blue is a must-have for anyone with a cassette- or portable toilet. Grab this to keep everything fresh in your portable toilet without the work.