On 27/03/2012 21:04, tigerlily24 wrote:
Hello

I hoping someone can help me. We've got a little courtyard with raised
beds. It's so small I thought it'd be great if we could divert all the
lovely rain water from the roof on it's way down to earth. I'm intending
to install a water butt to the down pipe. My question is: would it be
possible to supply a timed irrigation system from the butt which
switched to the mains if the water ran out?

Get as large a butt as you can to make it worthwhile. Also, check the
specifications of the irrigation timers to ensure that they will operate
properly from a low water pressure. If you can mount the butt up fairly
high, that might help.

Just had a brainwave... Would it be possible to top up the water butt
from the mains?

All you need is a ballcock-type valve (as used in a toilet cistern)
placed as near as possible to the bottom of the water butt (but where it
can still open a little). The valve will then only open when the butt
is nearly empty, but will not allow mains-water in when there is even a
small amount of rain water in the butt.

--

Jeff