When you’ve at last secured a coveted lounge chair at the busy public pool or dipped your toes into a hot tub, the last thing you want to think about are germs and bodily secretions — but what if it makes all the difference in preserving your health? The more crowded public pools and hot tubs are, the most dangerous they can become. While most of us make it to the pool and back unscathed, it’s important to arm ourselves with knowledge to stave off rare infections and all-around gross encounters. Enjoy your afternoon in the pool, but first, take a look at these gross little-known facts about what lurks in the water.

  1. Hot tubs can help spread toxic shock syndrome. It’s a very rare occurrence, but according to Cosmopolitan, hot tubs with poorly maintained chlorine can put you at risk for infection. If someone who is a carrier of the bacteria that cause toxic shock syndrome spends some time in the hot tub before you get in, the bacteria can enter your system through cuts or scrapes.
  2. Swimming pools can give you diarrhea. According to the CDC, pools are often home to cryptosporidium, a chlorine-resistant parasite that can live in pool water for up to 10 days and cause vomiting and diarrhea. Swimmers with diarrhea can bring it into the pool with them and infect others. From 2011-2012, the illness impacted almost 1,800 people, and 95 of them were taken to the hospital. Another diarrhea-causing parasite, the chlorine-resistant Giardia, can also be spread through pools, especially when a swimmer swallows contaminated water.
  3. Hot tubs increase your risk of heat stroke, especially after drinking alcohol. This one may seem obvious, as hot tubs can drive up your body temperature, but this risk becomes even higher if you’ve had a Mai Tai or two before taking a dip. Cosmopolitan reports that alcohol can speed up dehydration and a buzz can make it harder for you to pick up on your body’s warnings that something isn’t right.
  4. Open wounds can attract bacteria. This one is probably common knowledge to most pool-goers, but just in case – the CDC warns that dangerous bacteria can enter the body through an open wound, and the risk of spreading bacteria to other swimmers also exists. As most of us know, Band-aids aren’t allowed in the pool either, so if your cut is an open sore that can’t go uncovered, sit swimming out. It’s worth avoiding a serious illness or infection.
  5. Herpes can spread in hot tubs. According to the CDC, in very rare cases, hot tub loungers may be able to contract genital herpes if another lounger is experiencing an outbreak.