If you have not read this article, Which Is Dirtier: Your Reusable Water Bottle or a Toilet Seat? by HILLARY EATON Last Updated: Sep 23, 2016 you really should.
It is an interesting article and it really drives home the point that reusable water containers should be cleaned periodically. I also like how the article lists different types of bottle containers and lists the bacterial count for each type of container.
Staying on top of bacteria should be a priority. At Midwest Laboratories we look at all kinds of samples like food, water, production lines and look at bacterial counts to help companies better manage their processes to minimize the presence of harmful bacteria.
According to the article, a normal bacterial count for a toilet is 27 CFU/sq cm. In the study, some bottles were analyzed for bacterial counts of 900,000 CFU/sq. cm.
Something to really think about and learn from.