Dear Habib:

In helping to make your project, first of all you need to consider that
your pretension is to construct a vessel, or a floating structure.

If you construct a underground water storage, your first task is to make
it a non floating one. The best logical way to anchor the storage, is
to make it heavy enough in order to make it structurally statically
stable. And by the way, a heavy simple concrete would be a good choice
(steel reinforced for temperature and shrinkage only). You should use an
aditive to make your concrete imprevious.

An alternative is to buy a High Density Polietilene Water Tank.

The best alternative I think it is, to make your storage
semi-underground, (or better yet a superficial one), avoiding as
possible the location under the water table, and pump the water up with
a windmill if possible, for this kind of pump is one of the cheapest of
all, I hope in your country you can buy one, or find blueprints to
construct one by yourself.

And if your choice will be an underground one, avoid brick masonry, it
is not impervious, because your stored water will be contaminated by the
outside brackish groundwater. Remember that your investment will be for
your lifetime.

Some useful links:

http://en.wikipedia.org/wiki/Windmill

http://en.wikipedia.org/wiki/Image:Texas_Windmill.JPG

I'm not endorsing this supplier, this info is for make a picture of what
I'm talking about:

http://www.koenderswindmills.com/Koenders_Windmills_AirDr.html

This site is an entertaining one, and maybe you may buy blueprints of
watermills:

http://www.windmillersgazette.com/index.html


Greetings
José Luis Nava
from Cuernavaca, México

--- In hydrologymodel@..., habib rehman <habib675@...>
wrote:
>
> Dear All,
>
> Can some one tell me the solution of following problem:
>
> I want to contruct an underground water strorage tank which will
receive water from canal for drinking purpose because the groundwater of
that area is brackish (project area is sindh, Pakistan). The dimension
of tank is 22 x 22 x 6 cft. The tank is brick masonry. But during
excavation underground saline water appear at a depth of 3 ft. So now
what should I do, what material in foundation and at side walls I should
use so that the structure remain economical and strong enough.
>
> Regards,
>
> Habib
>