The Best Premium Portable Waste Tank. This ingenious tank is in a class by itself. Completely self-contained so there are no required accessories to buy or parts to store. Each model has up to 20 Percent more capacity than competitive models for fewer fill-ups - saving time and effort. Thetford's improved SmartTote™ saves time, effort and hassle. PermaStore™ hose stays connected to tank and collapses into pivoting cradle for neat, compact storage. AutoStop™ gauge prevents messy overfilling.