Water Tanks, page-109

Zero would also need to engineer a fall over the length of the 50m pipe to keep it dry so the weight would only be the pipe, as long as it didn't sag anywhere. These aerial pipes would also surround the house to mimic the current below ground manifold that serves all of the downpipes. That means the fall would start at the far side of the house to the tank side, bringing them below head height on the opposite side of the house and the tank 50m away would have to be well below the house level to keep the pipes dry with enough fall. It would be a disaster if the water collected anywhere because the weught would bring it all down.

I can appreciate it would be great to have but in reality it's totally impractical and an eyesore.
If the house pad was cut into the side of a hill you might be able to radiate the pipes away from the gutter to the sloping hill and down to a tank below, also cut into the hill?