A little petrol powered pump? Available new for less than a few hundred quid. I have a similar situation except the water has to be carried in the tank about 400 yards to where I need it. My solution is a pump to fill the tank, pallet forks on the tractor 3 point linkage, and drive it up and place it wherever I want. Big advantage is I can still move the IBC even when it's got water in it, so don't have to empty it to free up the trailer for any other jobs.