When it comes to pools, you never know what kind of germs and parasites may be lurking below the surface.
"E Coli, Giardia, Campylobacter, Norovirus. There's a lot," said Consumer Reports Health Editor Catherine Roberts.
The most common culprit when it comes to swimming-related illnesses-- is Cryptosporidium or Crypto for short. It's spread through fecal matter...even a small amount of which can contain millions of germs. Vincent Groppa has been in the pool business for 35 years.
"If a child has an accident in the pool or there's any type of elimination in the pool, we know that we have to treat it right away," said Gunite Pools Vincent Groppa.
That is because regular levels of chlorine won't kill Crypto, which can survive in a well-maintained pool for up to ten days. It's also easy to catch. The CDC says swallowing even a mouthful of water infected with Crypto can lead to weeks of diarrhea, nausea, and vomiting.
"They should not be swallowing the water and they shouldn't be going to the bathroom in the pool," said Roberts.
To protect yourself and your family, make sure anyone who swims in your pool follows some simple guidelines.
"Anyone who is experiencing diarrhea or has been sick should not swim. Have people take a shower or at least rinse off before they swim," said Roberts.
Also, have kids take frequent bathroom breaks to reduce the risk of accidents. That goes for babies as well.
"Those swim diapers are not foolproof," said Roberts.
Groppa says, if the fecal matter does get into the pool, don't take any chances.
"Everybody out of the water. Shut it down," said Groppa.
The only way to effectively kill crypto, he says, is to have a professional super-chlorinate the water and then slowly bring it back to normal levels again -- a process that can take at least 8 hours.
"It's like a super germ, you know, so that's the only way to take it out of the pool," said Groppa.
Parasites and dangerous bacteria in pool water