Shower water and bacteria?


My cousin's biology teacher told her class that the water we shower in is not hot enough to actually kill bacteria but it promotes bacteria to grow through its warmth. He said it is best to take as cool a shower as one can stand. Is this true?

— Freaked about bacteria

Dear Freaked about bacteria,

Before giving hot showers the cold shoulder, it’s good to keep in mind that not all bacteria are bad. However, it's not clear where you’re concerned about the bacteria growing — is it on your body, the water, the shower, or elsewhere? In one sense, your cousin's biology teacher is correct — the water temperature used for showering is not hot enough to kill bacteria. Fortunately, it's not necessary to kill bacteria on your skin when bathing; in fact, having some bacteria on your skin, depending on the type and amount, is normal and healthy. If you're concerned about the water itself, tap water contains low levels of bacteria (along with chemicals and minerals), although at safe levels as determined by government regulations. Still baffled by bacteria? Then keep reading!

Most folks have an array of bacteria (and other microorganisms) that peacefully and beneficially coexist on their skin under normal circumstances, and the skin is pretty effective at keeping them in check and from entering the body. However, damage to the body’s first line of defense can diminish its ability to protect it and throw off the balance of skin microorganisms. So, to keep your bacteria balanced, it may help to keep your skin moisturized and avoid irritants and harsh scrubs. Next time you’re in the shower, consider these hygiene tips that can help keep body odor at bay, but maintain skin health:

  • Stay warm. Contrary to the advice of your cousin's biology teacher, cold water is not as effective as hot water for removing dirt and bacteria. If warmer water is what you prefer, you may as well enjoy it instead of freezing your tail off, right?
  • Lather up. Soapy water washes away body oil, which holds excess bacteria on your skin. But, some people’s skin may be sensitive to heavily-scented soaps, so you might consider opting for an unscented option.
  • Scrub-a-dub-dub. Try using a washcloth or loofah sponge to rub off dead skin and germs. But, it's recommended you keep you loofah or washcloth well-maintained by rinsing them and letting them dry thoroughly between uses, and disinfecting or replacing them regularly.
  • Be wary of antibacterial soap. While they can kill germs, they may also contribute to the growing problem of "super germs" that antibiotics cannot fight. Using regular soap can get the job done, so consider limiting the use of germ-killing soap in the shower.

If you're concerned about bacteria in the water itself, you may be happy to know that almost all municipalities in the United States use a chlorination process to disinfect the public water supply, virtually eliminating any disease-causing organisms in the water. To learn more about quality testing and decontamination process of tap water, check out the Drinking Water FAQs from the Centers for Disease Control and Prevention (CDC). However, despite vigilant efforts, some bacteria do survive. Although being sprayed in the face with bacteria may seem gross, most of these tiny organisms are quite harmless, and many are actually good for you! But, it may also be helpful to keep in mind that not everyone relies on public water supplies, which leaves them responsible for quality testing their water (to learn more, take a look at Water Quality & Testing from the CDC).

Germs from water notwithstanding, the actual shower stall or tub is a prime site for bacteria growth. Consider the following to keep your personal spa spic and span:

  • Clean or replace the shower curtain often. Soap scum on the curtain can be home to a bustling community of microorganisms.  
  • Run the water, just for half a minute before you hop in the shower. Bacteria like to congregate in the shower head, so running the water flushes out some of the germs. If you're concerned about wasting water, consider filling up a bucket to use to water plants.
  • Upgrade to a metal shower head. Plastic spouts are more hospitable to bacteria.
  • Scrub the tub. Pick your cleaning agent of choice and scrub the scum out of your tub regularly.

It may be a little freaky to think of bacteria taking over your shower. Fear not though — your skin and immune system offer good protection against all kinds of germs. However, folks who have compromised immune systems, are prone to skin infections, or are about to go through surgery are recommended to keep their bathroom in tip-top shape. These same individuals may also want to talk with a health care provider to determine if a different hygiene strategy may be appropriate. In most cases, comfortably warm (not scalding), soapy water is enough to keep your body fresh and clean, and dozens of cleaning products are available for sanitizing your shower.

Here's to keeping clean!

Last updated Apr 07, 2017
Originally published Dec 01, 1994

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