No. The water of the central water tank is also used for tap water and shower water, so that’s why you should not add Thetford Aqua Rinse Plus in your central water tank.
You can use Thetford Aqua Rinse SPRAY instead. It’s an innovative rinse solution which is especially developed for toilets connected to the central water tank. You spray the inside of the toilet bowl with Thetford Aqua Rinse Spray before or after flushing the toilet. It coats the toilet bowl with a protective layer providing a smoother flush, it saves water as fewer flushes are required and it smells fresh long after spraying.