Have your eyes ever gotten red after swimming? Guess what? The National Swimming Pool Foundation says that's usually because of urine in the water.
Dr. Eric Higginbotham with Dell Children's Hospital says in some cases it's a high amount of chlorine.
"The urea in urine is one of these compounds that can irritate your eyes as well. So either way it's not a good thing," he said.
But he says there's a bigger problem.
"It's more people that get into pools with diarrhea where within that diarrhea there's different types of bacteria, different types of viruses. The one that the CDC has been talking about recently is the Cryptosporidium," Higginbotham said.
In a recent CDC report, there were 69 outbreaks of illness associated with treated recreational water -- like swimming pools -- from 2011 to 2012, the most recent data available.
Cryptosporidium was the culprit in more than half of them.
Dr. Higginbotham says it can be spread by swallowing fecal matter in a pool. So bottom line, if you or your kids have diarrhea, don't go swimming.
On the other hand, there's natural water, like Bull Creek.
Karen Baumann prefers it over chlorine.
"This has its advantages and disadvantages as well but the water's moving and it's just fun, this is a really I think a fun place to come to because of the falls," she said.
Dr. Higginbotham says the recent floods have caused some problems so stay away from stagnant water.
"There's a type of bacteria called Aeromonas which is in stagnant water. You get a cut or a scrape, that scrape gets infected with this Aeromonas and then you get a really sort of terrible soft tissue infection that we recently had a few cases here that had to be admitted...IV, antibiotics," he said.
The City of Austin says as for places like Bull Creek, their rule of thumb is to wait 3 days after a big rain to go swimming.
Some swimming tips from the CDC:
Stay out if you have diarrhea
Shower before you get in the water
Don't treat the pool like a toilet
Don't swallow the water
The City of Austin says for Lady Bird Lake and city creeks, use common sense. If it's murky, don't go in.
Out in the county, Hamilton Pool is a popular place. Unfortunately, it is not open for swimming right now due to high bacteria and flood damage.