The empty tank turned out to be a blessing in disguise, because I had wanted an isolation valve installed between the existing tap and the tank, when the tank was installed, but the installer did not comply with my wishes. The isolation valve was required so that if I wanted to connect a pump at some time in the future, I could remove the tap, without loosing all the stored water.
So, today, to make things right, and turn this stuff up into an opportunity, I found an old brass isolation valve in the shed, left over from some irrigation pipes I removed when the new deck was built. All I needed to connect it all up was a brass three quarter inch male to male joiner. One trip to Bunnings later and a $1.70 poorer, the new valve and old tap were in place, with the assistance of a liberal application of Teflon plumbers tape to ensure a watertight join. Now, I can remove the tap at any time and connect a pump (solar powered of course) when I can pick one up cheap. All this watering can usage is becoming a bit tiring and is not very good for my back. I am keeping my eye on Ebay and fingers crossed, will have something soon for the right price.
Now all I have to do is another rain dance to fill the tank up again!