How to avoid a foul scented water bottle on long hikes!
One aspect of reusing a water bottle on long hikes is that after a few days the water inside starts to get stale and develops a unpleasant scent. This can be the case even if you empty the bottle, rinse it and then refill it. This is due to bacteria growth inside this moisture rich environment. Bacteria thrives in water (for example algae or maybe the bacteria in your mouth that causes halitosis) or very humid environments.
This bacteria growth is then accelerated when the bottle is air tight such when the cap is closed. In elementary school we were shown a video of an experiment where two mason jars filled with tap water were left out. One was sealed tightly with the cap and the other left open. The video predicted that you would think the jar that was sealed would not be able to culture bacteria effectively. On the contrary the sealed jar had an accelerated rate of bacteria reproduction and after a few days the jar was filled with a cloudy liquid and the non sealed jar was only slightly discolored.
Even washed dishes and cups if not probably dried will retain bacteria or have bacteria grow within the moisture. drying a bottle, plate, or cup is important. A dry surface is not a hospitable environment for bacteria. I found that if i did wash my bottle but did not properly dry it the smell would quickly come back within a day or two.
Using this information I found that after every night of hiking if I let one of my bottles dry completely I could almost completely avoid the development of fowl taste or smell of my bottle. This was accomplished by draining the water from the bottle, then vigorously shaking excess water from the bottle and lastly placing the water upside down but in a manner that the mouth was not obstructed in any way. By drying out my bottles everyday I almost never had a bad sent or flavor to my water.