In article ,
"David Hare-Scott" wrote:


You don't fill cisterns?



I fill above ground house tanks holding 50 kl from roof water for
domestic use but that volume would be useless for the garden and in
any case must be reserved. I have a small dam for stock watering
holding 2.4 Ml that will keep the garden alive in emergencies but
that is uncovered and does lose some due to evaporation.

As I understand it a cistern is used in very dry climates (eg north
Africa) and it is covered like the former but as large as the
latter. This would be extremely expensive, certainly out of my
range.

D

I saw them in France. Why they feel they need them is anybody's guess,
as they get at least 2 - 3 days of rain every month.

In any event, in a cistern there is little evaporative loss of water
to heat, and wind as you find in ponds. A 25' x 45' cistern would be
expensive, no doubt. It was just an idea.

And only hold a tenth of my dam or less.

D

Sorry, error, 25' is the radius.

By 2.4Ml, am I to understand 2.4 million liters (= 84,755 cu.ft.)
which would be contained in a tank 50' in diameter and approximately 45'
tall. V = (pi * r^2) * height = 1962.5 sq. ft. * 45' = 1962.5.

In any event, there is no reason for the perfect to become the enemy of
the good.
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