To ensure consistency of approach, a uniform ban is normally applied to all customers who have their water supplied by the local water company. This includes older people and people with disabilities. Although we sympathise with the effects a hosepipe ban can have, it is for a water company to set the precise terms of a hosepipe ban or restriction.
Defra is currently in the process of updating the companies' powers to restrict the non-essential use of water. You can find more details on its website.