On Sun, 21 Sep 2008 11:46:02 +1000, David Hare-Scott wrote:

In my view the polymer ones are best. The polymer is UV stablized and
they have been in use for long enough to be sure that they will actually
last. Also they come in various colours and don't need painting. Concrete
will crack (especially on clay soil) and are very heavy, and galvanised
iron will rust (especially near the sea or in a polluted area). I have
three polymer ones from Bushman and I am happy with them.

Just to add 2c to the discussion.
If you are in a place bordering bushland, you might want to
reconsider poly tanks if you are relying on them to assist in fire
fighting, but if that is a serious consideration, then you'll have a
diesel powered pump in a brick enclosure and roof sprinklers as well I
guess.

I'm also thinking about repairing them. The old gal (new = colorbond)
could be easily repaired with a piece of tin and sticky goo. they seem to
rust out in the bottom if never cleaned out. I guess you'll need to be
able to fibreglass to properly repair a poly tank (anyone done it).

Generally get the biggest tank you can and make sure the ground under it
is VERY stable and compacted.

After you work out how to get the tank into place, you also need to
investigae all the costs. If you are going for the rebates,then you have
to hire professinals (plumber and electrician(?) AFAIK to sign off.


Something you need to work out is how in advance is how to re-arrange
your roof plumbing to capture the maximum amount of water, this is not
so easy if it was built to discharge at 3 or 4 different places. The
simple solution is to block the ends or downpipes where you don't want
the water.

Start from the top.
Work out how to keep leaves out of the gutter, but make sure you can
clean/flush the gutter as they are not the only crap that gets their (all
filters have small bits fall through, plus flower parts, bugs,
etc).

Then have a leaf diverter below the outlet and work out where the leaf
diverter is going throw the leaves and a bit of moisture.

The "sydney standard" says I should have 3x100mm down pipes. Like everyone
else, I have 2x90mm, but my front downpipes are long horizontal runs down
each side of the house. Different yes, but I'd loose most of my
water if I didn't. Until SWMBO agrees to replace the front lawn
with a mega tank, then it stays that way.

Long horizontal runs are leaf catchers, which is why I mentioned the two
steps above.

I also have a first flush diverter (put T vertical just before the
downpipes(2 on each tank) enter the tanks(2).