Even though we pour buckets of chlorine into them yearly, our swimming pools aren’t always clean. In fact, there are many common infections that thousands of people get from a swimming pool every year. Should you be blaming your stomachache on your pool? Or are you at risk of catching something more serious in the water? Here are some diseases you can get from pools that you should be aware of.

1. Cryptosporidium

While there is no name for the illness that cryptosporidium causes, it is the leading infection that people get from pools in Florida. Getting even a small amount of this microscopic parasite in your mouth can end up causing three weeks of diarrhea, stomach pain, nausea, vomiting and sometimes a cough.

The problem with cryptosporidium is that it is highly resistant to chlorine and very difficult to remove from a pool once its there. Tens of thousands of people will get this infection every year. There is only one drug that helps treat it, but doctors can also help make people more comfortable while their bodies deal with the infection.

2. Hot Tub Rash and Swimmer’s Ear

Both of these illnesses are caused by pseudomonas, a common bacteria found in improperly treated water and in hospital settings too. When it causes hot tub rash it infects your skin and may create pus-filled blisters. When it causes swimmer’s ear it is, of course, an infection of the ear, which needs to be treated quickly as ears are sensitive and the infection can damage your eardrum.

Swimmers may get mild or severe forms of this infection that may need to be treated by antibiotics. Some forms of pseudomonas are becoming antibiotic resistant.

3. E. Coli

E. coli is a common infection from food that hasn’t been kept clean, but you can also get it from a pool too. If you swallow it, you may end up with a mild fever, severe stomach cramps, vomiting and diarrhea. While some people handle E. coli infections pretty quickly, other people can be seriously sick for many days and end up needing medical care to recover.

4. Giardiasis

Giardiasis is yet another parasite infection you can get from a swimming pool that will end up giving you diarrhea. This infection is caused by ingesting giardia, which may cause more than just a short-term stomachache. Even after the infection has resolved with medications, you can still be in pain for weeks or months afterwards. You may also suffer from fatigue, gas, nausea, weight loss, and other uncomfortable side effects.

5. Legionnaires’ Disease

If you get infected with the bacteria legionella, then you may develop Legionnaires’ disease. It’s most likely you’ll get it if you breathe in the mist above the pool, and that mist happens to have legionella in it. The disease is like a severe form of pneumonia, which inflames your lungs. Antibiotics is the proper treatment for Legionnaires’ disease. It’s more likely you get this disease if you’re immunocompromised. People with strong immune systems may get a milder infection.