Disabled have been exempt for many years Den. It was done mainly for those who might need 2 sticks or wheelchair so unable to carry watering cans.
I have used cans and water butts for many years but that water has run dry now.
Disabled are also allowed to hosepipe wash cars. I generally dont was the car during a drought period, then, when it rains, i wash it during the rainfall.
We dont run out here so quite lucky. Not sure how much is stored locally or where the resevoir is