Reusable water bottles are only growing in popularity, but health experts say if they're not cleaned regularly, they could be growing mold. The good news is most of the time it is not black mold that will make you sick.

To prevent it, you should wash your water bottles like you wash your hands. Use warm, soapy water for 20 seconds and be sure to take it all apart. That includes removing the straw, the plastic or rubber seals that keep the liquid in — anything that can be removed. Dissasemble everything and give it a little care.

After you’re done washing it, rinse three times with warm water. You don't have to fill the bottle, just rinse the surface and shake it around.

It’s also important you let it dry completely.

You can also use a quarter cup of white vinegar in the cleaning process and even squirt it through the straw. With this method, you don’t have to rinse. Just let it dry, and if it still smells like vinegar in the morning, you can do a quick rinse before filling it up.

Experts give a thumbs down to dishwashers and say you should wash daily.

"Sometimes these molds and bacteria are growing and very thin, little biofilms and so that's why you really want to rub the surface with a sponge, a bottle brush or whatever," said Dr. Thomas Melendy, director of the Witebsky Center for Microbial Pathogenesis and Immunology at the University at Buffalo. "Do you have to get everything perfectly 100%? No. But you want to do a good job. Goes back to your ABCs, right?"

In terms of material, stainless steel and glass are most recommended.

Doctors say a stomachache is most common if you drink mold, but it can lead to other issues if you’re not careful.