put the tank inside

https://www.youtube.com/watch?v=f7uFiIQzH7c

Grand Designs Australia S02E07 Stonyfell Watertank

@ 750,00 Au it may be out of most permies' budget
but the man has some cool ideas

I have a kids book that shows different types of houses all over the world and there is actually a place where people have been building houses for maybe a thousand years? where the roof is like this. it is a funnel and all the water goes into a storage area inside. I will look for my book later so I can find out where that is.

their houses are much greener in materials they are made with but they are also much smaller houses

26 THOUSAND gallons. That will give you some thermal mass.

The hip roof fabric roof should be an awesome cooling feature, shading the main house.

Not going to work for somewhere that gets snow. He needs to have a surge capacity and overflow for gully washers, but I am sure he engineered that in.

I would take that house. Not at that price, but I think the idea is sound.