Nurses have slammed "draconian" rules which stop them from drinking water during their shifts.
Many say are unable to take breaks to eat or drink water due to staff shortages and high workloads.
The topic of hydration was debated at the Royal College of Nursing (RCN) annual conference in Belfast on Sunday.
Alison Upton, a member of the RCN UK Safety Reps Committee, told the congress that "draconian" rules at some hospitals do not allow staff to bring water bottles into clinical areas.
"We know that staff go without breaks - this is wrong," she said.
"Health care workers are missing breaks to provide holistic care for service users.
"They are letting their own nutritional and hydration needs fall below the daily recommendations.
"How is it then acceptable to deny them a water bottle close to hand to at least ensure that they can maintain hydration."
Some of the reasons against having water bottles in view are that it "doesn't look good", or "makes staff look lazy", she added.
"I see no reason why a water bottle can't be in view."
Staff at West Suffolk Foundation Trust have been given water bottles, specifically chosen to meet infection prevention needs, in a bid to combat the problem of dehydration.
Rowan Procter, executive chief nurse, said: "Patients are constantly reminded to drink and ensure they are well hydrated but staff often forget about themselves."
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