We are always looking for unusual uses for water tanks, and at a caravan park in Cooper Pedy, they have a couple of huge water tanks which have been pulled into service as unusual storage.
One tank contains a large swimming pool (and the pool itself looks like another water tank!). It gets extremely hot in Cooper Pedy, so having the pool under cover maintains a much more reasonable temperature than outside.
Another tank contains a comprehensive TV/Games room..
Have you seen any other uses for water tanks?