Is it OK to reuse water bottles?
Feb. 26, 2008 by Lisa Currie
If you drink water from a bottle, thoroughly clean or replace the bottle often, says the Mayo Clinic. 
Resist the temptation to refill the small, single-use plastic bottles that water, soft drinks, milk and juice sometimes are sold in. Bacteria from your mouth can be tough to clean from these bottles, even if you use the dishwasher.
Better yet, purchase reuseable bottles — there are plenty of options out there, though stainless steel is the absolute best material — and reduce your impact on the environment at the same time.