We used one in the past but it now sits in the rafters of the garage (in case of drought!) because it takes up too much room in the trailer; it holds too much water which doesn't get used up and its horribly heavy to get up onto the stand when full. We changed to a collapsible water carrier which concertinas down for packing. We are tent people so it maybe perfectly convenient for caravans.
I replaced my 29L Aquaroll with a 40L Aquaroll from Halfords when they had them on offer at £32.99 but this was last season, it may be worth checking out their prices this season. I also got a Wastemaster from them at the same price, thought they were very good offers at the time.