Pete C. wrote:

I'm sorry to say (ok, not so sorry) that you are way, way off base
there. Large rainwater collection tanks are very common in many parts of
the world and work just fine. Indeed I seem to recall This Old House did
a project in Bermuda and spent most of one episode covering the
rainwater tanks that provide the bulk of the domestic water there.

Pete C.

G'day Pete
Thanks for the tip, I'll have a look at their online site to see if
there is some sort of transcript on these systems.
Being in Australia, I haven't seen that show, although it's probably on
cable somewhere.
Cheers
Wayne