Following on from my crop watering thread it looks like more storage capacity and a more controlled watering system are whats needed.
Regarding the storage I have been looking at the prices for IBC's, and for new ones they seem to start around the £150 - £175 mark which isn't cheap. Second hand ones are available for around £50 but I would need to be 100% sure of what had been stored in them beforehand.
There is also the problem of getting the bosses approval to stick a couple of them in the back garden - they don't tend to blend in very well

. Burying is an option, (and a lot of work) but then you will need pumps etc, increasing the cost and adding complications
Another option that will blend in a bit more is a garden pond filled from a downpipe with the overflow directed back to the drains (using a pond in place of a butt or IBC).
I am often in huge industrial scale Nurseries (the type that supply the supermarkets, not the garden centre type) and most of these places have now built massive water collection ponds/lakes the size of football pitches. They are filled by the runoff from the acres of greenhouses surrounding them. The nurseries do this so that they can cut down on the amount of water (and water bills) they use from the mains.
I have inherited a couple of smallish ponds in our garden, I may look at replacing one of them with a much bigger one.
Any thoughts ?