Elsan Fresh Water Tank Clean 1lt

I use this product to periodically, perhaps twice a year, or more if the caravan has sat for a while without use, to cleanse the fresh water system. This is then followed by a pump out using the Floe° technique. The alternative product is CleanTabs Puriclean, but this seems, for me, to require more fresh water rinses than the Elsan, and it is 'powdery' in consistency even after thoroughly diluting and mixing. Elsan products are, I feel, more difficult to obtain, especially locally (Thetford being the easiest) but Elsan is a far superior product and worth sourcing.