Multi purpose waste container

The sums used by the OP, don’t really add up. I presume that the £3.90/day saving is through not using a superpitch. But unlike super pitch users, he’s walking to and fro from the water and disposal points, so he’d also be saving £3.90 by staying on a standard pitch. We use a barrel of water/day in our caravan as we both shower every day and cook/ wash up from home cooked meals, including pots and pans. A toilet cassette holds under 20 litres, while a wastemaster is large enough to catch the entire used contents of a 50 litre barrel. Everyone to their own, but we’re not likely to be following the OP’s example.