Hi Folks,

I have finally installed a rain water tank.  I now fill my 19 litre
water cooler bottle from a small tap that I have piped into the house
at floor level.

Its a pain to fill as it is slow and the tap under the sink is awkward
to get to.

What I would like to do is sense the level in the cooler resevoir and
use a pump to top it up as it is used.

The tank and cooler hieghts require that I pump and shut off the flow
as the level in the water tank can be above or below the level of the
cooler.

I want to minimise on standby current, minimise on price and come up
with an elegant solution.  Naturally.

I have come up with 3 solutions.

1. Using a small easily available cheap windscreen washer pump, pump
the water up thru a loop of water pipe that extends above the top of
the water tank and then flows down thru pipe to the water cooler.  At
the apex of the water pipe loop at a point above the water tank
install something like a shephards crook so there is an opening to
air.

This will allow the water to be pumped up under pump pressure then
flow down to the cooler under gravity.  Once the pump is shut off the
water remaining on the tank side of the loop will return to the tank
and on the water cooler side will empty into the water cooler.  ie
there will be no syphon action as there will be an opening at the apex
of the loop.

I like this solution but is a little untidy plumbing wise and results
in more pipe exposed to the sun and I dont think it is good to have
rainwater at raised temperatures.

2. Use a sqeeze pump (do they use another name for these) like the
ones used to deliver accurate doses for medical purposes.  For me this
is difficult to build or aquire.  I like this as it provides a method
that combines pumping and shutting of the flow in one device.

3. Use a windscreen washer pump and a solenoid.  This is not a bad
idea but I cant seem to find small solenoid valves and havent
experimented (as I have none) to see if they significantly restrict
flow.  Most of these that I can source are desgned for irrigation and
as such the pressure they control would be quite high compared with
what a windscreen pump can deliver and not sure if they would work at
all.

Anyone have any clever solutions or know a good source of low pressure
smallish solenoid valves (in Perth Western Australia).

I think I have the control side of things sorted.  I considered reed
switch with floating magnet but I have decided to just use a probe
that detects the level of water by the drop in resistance.

Thanks for your time.  Any help greatly appreciated.

Cheers Justin
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