NHS managers affected by last year's floods have accused their water supplier of an 'inadequate' and 'unco-ordinated' response to the emergency.
A Department of Health report on lessons learned from the summer 2007 floods in Gloucestershire and Yorkshire reveals trust staff in Gloucestershire had to distribute tonnes of bottled water and even decontaminate systems at the height of the crisis.
It says supplier Severn Trent Water "has a lack of infrastructure to deal with such an emergency".
The company could not supply enough drinking water and, as the crisis unfolded, dumped 13 tonnes of bottled water on the edge of Cheltenham general hospital's grounds, leaving staff to distribute it.
When the hospital ran out of space for empty bottles, staff were told to take them home. Once mains drinking water had been restored, water systems at Gloucestershire Hospitals foundation trust had to be decontaminated.
But the water company refused to increase chlorination in line with DH guidance, the report says, forcing trust employees to "super-chlorinate" the water themselves. This took 60 people nearly six weeks, resulting in an extra 3,000 hours of work.
In addition, "inadequate vehicles, without the right pumping equipment, proved problematic" and "contingency plans, whilst tested, did not deliver successfully when the real incident arrived," the report says.
Gloucestershire Hospitals director of property and medical engineering Graham Marsh said: "Severn Trent were totally out of their depth. They have committed to supply this hospital. There's no alternative supplier. They let themselves down."
A Severn Trent Water spokeswoman said: "We accept that, like many other agencies involved, our plans could have been more robust, and have taken steps to address this. We have made improvements in flood defences, in long-term water supply resilience which means we will be able to substitute one key asset with another without loss of supply, and in contingency planning should supplies fail."
In South Yorkshire, the report recommended trusts develop better communication systems with electricity suppliers, as staff were not told about planned shutdown times.
Hull and East Yorkshire Hospitals trust needed to review its internal procedures for business continuity and address "issues of inconsistency" around staff leaving the workplace early.
NHS sustainable development unit director David Pencheon said the health service needed to do more to prepare itself as flooding becomes more common.