lentildude writes:
Hi, I live in the lowerbluemountains SYD, (10 mins Penrith) and really
want to splurge on a large watertank 9000 - 20000litres. Really
confused what to get, I want the best value tank that will last at
least 20 yrs. Anyone know any bargains out there?? There are a few
sellers on EBAY but worried buying sight unseen. If I connect it to
the growing shed and not the house do I still get a govt rebate? Any
tips appreciated.

The poly tank does seem reliable and robust and is easy to transport
and move if you decide it's original placement is not quite right. I'm
not sure whether they have been around long enough to be confident that
they'll last as long as the gal tanks or the precast concrete ones in
the sun (e.g., 75 years, whatever). Certainly, most say they are
UV-stabilised but whether some withstand direct sun better than others
who knows?

Instead of 'having all your eggs in one basket' you can have multiple
tanks, but you'll probably find that the rebate is available only on
the first, so install the biggest capacity tank first. Identical
capacities come in different shapes, and naturally you'd buy tanks that
sit no higher than your roof gutters (unless you intend some clever
pumping during rain). It is feasible to bury the lower portion of a
tank to allow use of a taller one, but there is always the chance that
it will float up in the hole if the tank is empty when the hole fills
during a storm.

It's instructive to examine brochures from a number of poly tank
manufacturers. If you are getting a tall tank, you'd want to make
sure that its wall thickness increases towards the base of the tank.

If you have a high house and want to raise the tank onto a stand, then
the stand is likely to cost more than the tank! But a high tank means
that you are not held hostage to a pressure pump for gardening, and a
reliable 240 supply during hosing down during bushfire weather. The
poly tanks are happy to sit on a bed of builder's sand (the stuff that
has clay in it, and sets like cement with time). Make sure that the
edges can't get eroded over the years, and protect the tank from
accidental scraping from passing tractors, etc.

Pressure pumps, while giving the convenience of mains pressure, have
a sinister side: while you are at work they can completely empty your
tank, and if you are really unlucky, dump it all onto your bathroom
floor. An advantage of placing the pressure pump where you will hear
it in operation is so that in the middle of the night you can ask
yourself, "Why is that pump going?!" and in short time discover that
someone has left a garden tap turned on.

There have been cases during drought of someone returning home to find
that their precious store of rainwater has been spirited away by a tanker
truck during their absence.
--
John Savage (my news address is not valid for email)