It seems every day a new drink filled with electrolytes hits the shelves.

Advertisements tell us we need electrolytes to stay hydrated in the heat and during workouts. But how much do we really need?

"If you're outside in the heat, when you're perspiring, you are losing a lot of electrolytes," said Dr. Gaurang Shah, Assistant Medical Director of the Emergency Room at St. David's Medical Center. "You need to replenish the electrolytes in that scenario or if you're doing high-intensity sports or working out for an extended period of time."

Dr. Shah recommends everyone drink about one-half of a gallon of water each day and drink more if they perspire. Be mindful of sugary drinks such as Gatorade and Powerade. Avoid caffeine and alcohol when spending time in the sun.

Pediatrician Dr. Michael Holmes recommends giving children mostly water, but to supplement it with Pedialyte or Gatorade when they are moderately or severely dehydrated.

You don't always have to drink your electrolytes -- they come in food too.

"You'll get magnesium, sodium, potassium, calcium, as well as phosphorus -- so those are electrolytes that you'll get even in regular foods," Dr. Shah said.