Typically, patients undergoing major surgery involving anesthesia tend not to tolerate plain drinking Water. The intolerance goes away after 3-4 weeks. Don't know what this happens but our bodies work in mysterious ways.
When I did my surgery, the hospital actually recommended that I stay on broths, sugar free jells, sugar free popsicles, and Crystal Light (added to water). I couldn't stand drinking plain water for at least the first six weeks. Another tip is to freeze the water and suck on ice chunks.
Hope this helps.