the thermos could have had something in it from before. you may want to sanitize it with a mild bleach solution then let it air out well. i frequently store non boiled water over weekends or longer and have never had such an issue. the worst i ever get is that the water tastes bad after a few days or the interior walls of the bottle get slimy. you could have caught something from the gym too since it's an enclosed space with lots of people in it.
will storing non boiled water in thermo flask cause bacteria to grow? . hi . i recently started drinking non boiled water from a thermo flask ( sometimes kept for 3 or 4 days ) and ever since i started this i am getting cold mild fever or non stop sneezing without a break for over 3 weeks now. i used to go to gym before and i was fit everything was fine and cool until now. i have heard that water kept in dark area is prone to generate bad bacteria and can this be the cause for my trouble. any expert opinion on this? . thanks