Yes. As of July 2009, Colorado law requires you have a carbon monoxide detector installed within 15 feet of every sleeping area. That means 15 ft or less from the doorway of any room designed for sleeping. You see, your water heater may leak carbon monoxide a colorless odorless gas that can cause death. A detector will set off an alarm to alert you if there is a leak. This law applies to installing or replacing any fuel fired appliance.