Are there any health risks from reusing plastic water bottles by refilling them with tap water?

By Susan Brewer, Ph.D., University of Illinois,
Department of Food Science and Human Nutrition
 

As long as the water bottles have not been used for anything else other than drinkable (potable) water, they can be reused. The water should come from a safe source. Also, using a water bottle that has been used by someone else can be a potential source of viruses and bacteria that can be transmitted by contact with the mouth.
 
Source(s):
Water Quality for Consumers. Bottled Water Information. Cornell Extension Service.