I am about to build a house and I have the following challenge that I
would like some help with:
I live in a country where the water supply is at best inconsistent,
furthermore we suffer from periodic power cuts, particularly in
cyclonic period after which we can be without electricity for days.
Consequently most residential water systems are designed with:
a) an underground tank, to accumulate water and ensure stable supply -
typical size around 10 cubic meters.
b) a smaller (2-500liters) roof tank, feed from a pump somewhere
between the roof and the underground tank. This roof tank then
provides the pressure and water for the house.
Problem: With the roof-tank solution the water pressure is far from
what we are used to in the developed world, and problems often arises
when multiple outlets are used at the same time. I would like to have
a nice constant pressure, comparable with what one will find in Europe
or the States. At the same time, it is important that I have water
even when I am out of electricity.
I remember from my childhood, us having a pressure tank used with a
well and providing a nice pressure in all of the house - this is not
used much in this area for the reasons above, SO.. I was thinking -
would it be possible to design a system giving the best of both worlds
- in line with the following:
A) Underground tank as above
B) Pressure Tank feeding the house Cold water pipes and the
C) Solar Water heater - I live in the tropics so this can easily
provide 99% of hot water needed.
D) Roof tank, this would then be used when there is no electricity -
probably connected to the rest of the house plumbing incl the Solar
water heater via a set of non-return valves to avoid backflow from the
higher pressurised house system. Once the electricity is off, and the
pressure is down, the roof tank would then provide water for the
house. I was thinnking it would be fed directly from the pressure tank
and the level controled with a simple floater or something similar.
One problem I can foresee here is that the roof tank risk holding the
water for long periods, and thus the freshness could not be guaranteed
- I was therefore considering feeding external water points (garden
etc where the pressure is not as critical as it is in my shower) from
here to give at least some circulation in the roof tank. By the way,
we dont drink the water from the taps.
As I have absolutely no experiences with designing these kind of
system - I would like to hear from anyone who could comment on my
"design" and any good ideas/advice would be greatly appreciated.