...because weird stuff happens
Never Leave Bottled Water in Your Car
http://www.msn.com/en-us/health/healthtrending/firefighters-are-warning-people-to-never-leave-bottled-water-in-your-car/ar-AAqcjrM?li=BBmkt5R&ocid=spartandhp
I saw a video on Facebook the other day where a fellow started a fire by putting water into a clear plastic sandwich bag and using it to focus a sunbeam on some tinder.