When you have bought a water container, and put petrol or diesel in your car. Motor along to a near by stream or lake. This water is not fit to drink, but plants will love it. Garden centres sell the large water containers.
Take the water back home, and fill your watering can, repeatedly. Sread water over your flowers or lawn. The water is basically free. So no nasty chlorine, or water charges.
The water will run back, into the reservoir or lake. A water shortage, is irrelevant.
I live at Salford Quays. Little solar pumps will irrigate the grass, with canal water near by.