You may have scrubbed your toilet and scoured the mildew from your bathtub, but there is one bathroom locale you may not have thought germs would reside. And it could be making you sick.

It’s your shower head.

A new study from the University of Colorado shows that shower heads are havens for a type of bacteria known as Mycobacterium avium. According to the researchers, these germs are common in city water supplies and like to set up shop inside the moist confines of your shower.

Basically, that refreshing burst of water that blasts you awake in the morning as you’re lathering up could also be spraying microbes on you.

For most people, being exposed to these bacteria actually isn’t a big deal. However, the morning spray of germs could spell trouble for folks with compromised immune systems, such as people who have HIV or are undergoing treatment for cancer.

According to the Centers for Disease Control and Prevention, infection with Mycobacterium avium can cause respiratory problems and has been compared to tuberculosis. In people with HIV, it can also cause abdominal pain and other symptoms.

Unfortunately, shower heads aren’t that easy to clean and the study shows that bacteria tend to find their way back to faucets after cleaning.

But there are some ways to keep the bacteria at bay. The researchers advise choosing a metal shower head over a plastic one. Apparently, the plastic is just a little too cozy for the bacteria. Also, shower heads should be replaced periodically.

This should help you stay clean… with a few fewer microbial friends.