In the hot weather they should allow you the chance to drink more fluids, if they don't provide air con or give you regular breaks.
In many areas they won't allow you to keep an open container of water due to the infection control risks, but I can't see why it wouldn't be possible to keep this in the staff room (aside from the fact they'll have everyone rushing to the staff room every 10 mins).
Speak to your ward manager / sister and raise it as a concern. In the last few weeks I've had all sorts of people complaining to me.. Consultants, catering staff, therapists and various nursing staff. Most of the time the advice I give is usually that they should manage it locally, but there's no getting around the fact that sometimes you need air con.
