Follow CBSDFW.COM: Facebook | Twitter

NORTH TEXAS (CBS 11 NEWS) – In spite of the dangerously hot weather, the vast majority of North Texans Monday were heeding warnings to take the heat seriously.

READ MORE: Small Business Saturday Offers North Texans Another Day Of Deals And Steals

By late afternoon, only a couple of heat-related emergencies had been reported at area hospitals. And doctors add that keeping safe is really quite simple: limiting time in the sun and filling up on plain water. Just be careful, though, of where you keep it.

“My son is so funny,” says mother of three Kimberlee Norton, “he’ll ask me ‘Mommy, is this an old drink?’ So they know I’m paranoid about giving them water in old bottles or warm water that’s been setting out for a while.”

Norton says friends jokingly tease them about it… but, her family takes fresh water seriously. “My husband always keeps a cooler of water in our car when we go out on hot days, so we have fresh water in fresh water bottles.”

READ MORE: TCU Falls 48-14 To Iowa State

And it’s more than mother’s intuition. Studies have shown that under constant exposure to extreme heat, chemicals from the plastic bottles can contaminate the water.

“What we need to make sure is that water bottles are stored in a cool place,” says Jane Sadler, MD, at Baylor Medical Center Garland. “And even when they’re being used, that they’re not being left in the car and then re-drank after that because that creates other problems—you have to think about bacteria.”

Dr. Sadler also warns that the same can be said of the reusable water bottles. They need to be thoroughly washed daily—with particular attention paid to the small straws. “Bacteria love heat and it loves moisture… and if you think of all of the bacteria in your mouth, it’s being regenerated and rejuvenated within the bottle.”

MORE NEWS: Happy Black Friday! Experts Predict 159 Million People Ready To Shop This Weekend

(©2015 CBS Local Media, a division of CBS Radio Inc. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)