Now that summer is here, many of us will be spending more time at the pool. But as fun and refreshing as the water can be, it can also harbor bacteria and spread diarrhea and other illnesses.

"I think that whenever you go to a pool you have to assume that there are bacteria in the water or other infectious organisms that might cause you to be ill," said Dr. Susan Rehm, who treats infectious diseases at Cleveland Clinic.

She says germs like to surf on our bodies. The average swimmer can bring millions of microbes into the pool. Microbes are germs that can make you sick. Researchers for the centers for disease control say pool chemicals kill most of them within minutes, but some live for days. Our hair, nose, and skin products are full of them.

So, to decrease your chances of getting sick, Rehm says to shower before you get in the pool, swallow as little water as possible and never go swimming when you're under the weather - especially with diarrhea.

"Even if you don't have a problem while you're actually swimming in the pool the bacteria or viruses in your system can get into the water and infect other people, so don't go if you're sick," Rehm said.

Rehm recommends showering after swimming, too. She says to keep in mind that the pool is only as clean as we are.