The water in the cold water lines is getting warm while it is standing. Perhaps the hot water lines are nearby and are warming the cold pipes by convection. Your cold water pipes may also be running through areas of the structure (walls, ceilings, attics, etc) that are warm. The only thing you can do is try to insulate the pipes (both hot and cold). Insulating hot water pipe is always a godd idea, as it saves energy.
» This message has been edited by nicktheplumber on 15 September 2003