I am surprised no one has commented on Hospice and end of life care. It is quite common to restrict water intake for those with terminal disease.
I think the concrn here is not medically necessary restriction of oral intake, but actual neglect. If the NHS doctors in Britain are having to prescribe water to make nure nurses don't forget, there's a real problem.
The key thing is to "accompany" the dying. To be with them, sensitive to their individual needs. The presence of an alert, informed loved one, means everything.
(In my father's case, a thousand blessings upon my husband, who opened heart and home to my dear father in his declinign years and his time of passing on. A thousand blessings!)