Hmm, sounds like a great place for bacteria to grow...

You may want to consider food grade plastics or other materials that are
safe to be in contact with potable water.

My advice would be to leave the rain water for watering your vegetable
garden.

Regards,

Gordon Williams

----- Original Message ----- 
From: "Justin Richards" <justin.richards@gmail.com>
To: "Microcontroller discussion list - Public." <piclist@mit.edu>
Sent: Tuesday, June 17, 2008 9:21 PM
Subject: [OT]: How to keep a water cooler filled from a rainwater tank


> 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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