Some talk of having a large capacity abilityof storage is coming thru.
I ie. use those large blue plastic drums.
But for heating, I do not require it, as the drum/drums are kept in my fish room which is heated so the storage heating isn't required.
After reading the expense of the heater that was going to be used, I thought a bit. "Ya must be able to THAT cheaper"
Why not go to a "Farmlands" or similar, and get an immersion heater.,
I have a couple of these from the days before heating the whole room period.
Another thought is a replacement element for an electric jug.
Just drill a hole, insert with the supplied washers, and 'hey presto' a large electric jug.
You may need a thermostat set up, just in case a 'Senior Moment' hits, and you have an over heated LARGE amount of water.
Just some ramblings.
Alan