A little googling turns up a lot of discussion about reusing water bottles. The fear of bacterial and fungal seems to come largely from a single study of Canad

A little googling turns up a lot of discussion about reusing water bottles. The fear of bacterial and fungal seems to come largely from a single study of Canadian elementary-school students and the contamination may have come from their hands. There seems to be a consensus that if you occasionally wash the bottles with soap or let them sit with water containing a spoonful of bleach then reuse is okay. http://en.wikipedia.org/wiki/Reuse_of_water_bottles http://en.wikipedia.org/wiki/Reuse_of_water_bottles