Lap swimmers (former college, triathlete, and dedicated amateurs) tend to prefer a temperature between 76 and 79 degrees Fahrenheit. This range has proved to be most healthy for general lap swimming.
Warmer pool temperatures lead to higher energy costs and higher pool chemical costs, since bacteria grow more and faster at higher water temperatures.
While some argue that water temperature is a matter of personal preference, hot-water swimming can dangerously dehydrate and overheat even the most fit swimmers. In October 2010, a 26-year-old professional swimmer died from severe fatigue in a race held in 87-degree water.
Many community and YMCA pools raise temperatures to mollify vocal water aerobics groups, rather than requiring their trainers to provide active, healthy workouts. Also, many pools keep their temperatures higher because they do arthritis classes in the water - and usually, warmer temperatures can be initially more comfortable for arthritis sufferers. 85 degrees is the temperature the pool is at in the winter here in Hawaii for the arthritis classes principally. Generally there are not significant complaints from the lap swimmers (many of whom may choose instead to swim in the ocean water).
The recommended temperature for a single use facility that caters to lap swimmers, children and elderly is 79-82 degrees.