Could your reusable water bottle be a danger to your health? The Doctors investigate what is really living in your unwashed reusable water bottle.

 The Doctors grabbed 5 unwashed water bottles, each one a different design, and they sent them off to ABC laboratories to see just how dirty the bottles actually are. 

The Results: Plastic Bottles

The plastic water bottle came back with traces of several kinds of bacteria as well as yeast and mold. If you purchase a plastic reusable water bottle, make sure that it's not designed with hard to reach areas. Also, if you have the kind with a lid and attached straw, this is a potential breeding ground for mold as well. 

Once mold sets in, it will just keep growing and growing. For people with allergies and asthma, it can create a real problem!

Watch: Is There Mold in Your Child's Sippy Cup?

The Results: Glass Bottles

The glass reusable water bottle grew something called acinetobacter baumannii complex, which is a bacteria that could cause harm to an individual with a poor immune system, and is found in urine and wounds. 

Watch: 3 Unexpected Places Mold Could Be Growing In Your Home

The Results: Metal Bottles

Metal water bottles grew a few types of bacteria, which could also cause harm to individuals with compromised immune systems. 

"My concern here, and I always walk this fine line is, I don't want to freak people out to the point where they feel like they need to be overly cleanly. We are too cleanly in this society," says ER physician Dr. Travis Stork, who wants to remind us all that some bacteria is good. 

Based on the results from the lab, Dr. Travis recommends a BPA-free plastic bottle with a very wide mouth and lid as the best alternative for someone who wants to be environmentally conscious.