[TheForge] OT - Water pressure problem.

[Bruce Freeman]

Once again I'm using the broad knowledge base represented by this
group for an OT problem.

I have just installed rain barrels at all my downspouts, including a
250-gallon tank at one of them.  I plan to siphon or pump water
between them to maximize capacity.

However, none of these are more than 16" above the ground -- two
cement blocks.  That means that there's little water pressure
available, making using the water inconvenient.  I could rig a pump to
go on anytime I need water, but a more elegant solution would be to
use that pump to keep an elevated tank (water tower) filled between
limits.

What I'm thinking is to use a fairly small plastic tank -- 15 or 20
gallons (i.e., ~150 lbs maximum), and to mount it high enough to
provide reasonable water pressure.  In use, the pump would probably
come on every once in a while, because the tank would be fairly small,
but at least it wouldn't be running continuously or with no flow.

Now, to get 15psi I'd need a tower of over 30', and that's out of the
question.  I'd like something as low as possible and as small as
possible.  So, the first question is what is the lowest useful water
pressure for use around yard and garden?  I don't need to run
sprinklers, but would like to use drip hoses.

Possibly a water tower isn't the proper solution.  What other
solutions exist?  What I'm aware of is a pressurized system, in which
the pump fills an accumulator tank, or something of the sort, which
then discharges for a while before the pump comes on again.  This
strikes me as expensive, and i'd like to keep expenses low.

If it were possible to do, one potentially elegant solution would be
an accumulator tank that would be filled either with city water or
pumped rain water.  There'd have to be a barrier between them, and the
side that would accept the city water would have to be clean and
isolated from the rain water side (which must be assumed to be
contaminated with various environmental contaminants, not the least of
which would be bird feces).  If I put a check valve to keep the "city
water" from backing up into the city piping, this might even be legal!
 I toss it out mainly for discussion, as I really don't see much
advantage relative to an air bladder accumulator.

So, regale me with your wisdom, o metalworkers and artists of reality!
-- 
Bruce
NJ