"BigWallop" wrote in message ...

Just take the drop spout off the ball valve and stop it from syphoning back
out the tank. :-))


I didn't use a ball valve - electric solenoid valve from a washing
machine and water level sensor... When the mains pressure drops there
is a switch that prevents the valve from opening... Overkill but
enjoyable!

Because the house has only one circuit, the incoming main also feeds
the taps etc., hence the quick emptying...

I guess that the UK has regs to prevent this type of installation but
here... well, who knows...