It looks more than likely we will be charged for our water use in the near future. That being the case water tanks will be in demand. Barrels I'm afraid will not suffice. Manufacturers of plastic tanks will or should be already designing large water containers so that rain water can be utilised easily by the averge household.
What capacity do people think with be the standard?
The water butts sold nowadays are usually far to small. I would empty one in 20 minutes just watering a section of our garden.
(As a six year old child I remember trying to carry a white enamel bucket of water from a roadside pump to my Grannie's cottage......uphill. I think I arrived with a pint)