What’s the best temperature water to shower in to kill bacteria?

Dear Freaked about bacteria, 

It sounds like your cousin’s biology teacher might have muddied the waters for you, so hopefully this response can help clears things up. Certain groups of microorganisms naturally inhabit the human skin, forming a healthy microbiome. However, certain bacteria on your showerhead and in your bathroom can be harmful to your health. According to Centers for Disease Control and Prevention (CDC), water temperatures ranging from 130 to 140 degrees Fahrenheit(°F) can eliminate most of the harmful bacteria. However, be warned that these high temperatures can also increase the risk of scalding. One way to reduce the risk of exposure to harmful bacteria without risk of scalding is cleaning (and properly drying) your shower accessories. If you want to know more about bacteria and how to mitigate bacterial blooms, come on in, the water’s fine! 

Bacteria like to grow in damp and humid environments. This means that bathrooms, especially those with steamy showers, are an ideal place for bacteria to populate. In particular, bacteria can grow in loofahs, because the folds in the fabric trap moisture. Similarly, showerheads, shower curtains, and unwashed towels are breeding grounds for bacteria because of their dampness. Additionally, there are also bacteria that naturally exist in shower water. 

When it comes to killing bacteria, your cousin's biology teacher is correct—water temperatures that are safe for showering aren’t hot enough to kill bacteria. And it’s not recommended to try to withstand water that’s hot enough to kill bacteria because as previously mentioned, it can scald you. Additionally, it can even damage the skin’s ability to protect itself from bacteria and germs. That said, the teacher’s tip about showering in the cold water may have been prompted by research on the impact of cold showers on health. Scientists continue to study cold-water immersion. Self-reported evidence on the health benefits of cold-water exposure includes stress regulation, immunity boost, and increase in blood circulation. However, many of the claims remain unbacked by any hard scientific evidence. It is worth noting that jumping from standard room temperature into frigid water can raise breathing rate, heart rate, and blood pressure. If you have a heart condition or take medications that already alters your blood pressure or heart rate, you might want to avoid plunging into polar conditions. 

The good news is there are other methods, unrelated to your shower’s temperature, that can help protect you from harmful bacteria. In most cases, comfortably warm soapy water is enough to keep your body fresh and clean. You can keep bathroom bacteria at bay by cleaning your tub and showerhead frequently and replacing the shower curtain often. You can also keep your loofah, washcloth, and towel well-maintained by washing them and letting them dry thoroughly between uses. Additionally, you might consider upgrading to a metal shower head—plastic spouts are more hospitable to bacteria. 

It may also be comforting to know that the government tries to kill waterborne bacteria—most municipalities in the United States use a chlorination process to disinfect the public water supply. This kills many of the contaminants in the water supply. However, some bacteria do survive. You can further protect yourself from these chlorination-resistant bacteria by placing a plastic bag over the showerhead and running the water for a few minutes before you hop in. If you're concerned about wasting water, you might consider using the leftover water for plants. 

Feel free to stop giving hot showers the cold shoulder!