The Ultimate Towel Test – Separating Fact from Fiction

[#Beginning of Shooting Data Section] Nikon D2X 2006/06/28 16:26:11.1 RAW (12-bit) Image Size: Large (4288 x 2848) Lens: 50mm F/1.4 D Focal Length: 50mm Exposure Mode: Aperture Priority Metering Mode: Multi-Pattern 1/1000 sec - F/1.4 Exposure Comp.: +1.3 EV Sensitivity: ISO 100 Optimize Image: White Balance: Auto AF Mode: AF-S Flash Sync Mode: Not Attached Color Mode: Mode I (Adobe RGB) Tone Comp.: Auto Hue Adjustment: 0¡ Saturation: Normal Sharpening: Normal Image Comment: Long Exposure NR: Off High ISO NR: Off [#End of Shooting Data Section]

According to a recent Doctor Oz poll, there is not a lot of consensus on how long you should use a towel for.  Some (16%) say they wash their towels daily, while most people say they do so less often, with 33% washing their towels two or three times per week, 40% once a week, and 11% said they wash their towels only every 2 weeks or more.

Washing your towels after every use may feel a bit excessive since it uses a lot of water and energy, and may wear down your towels more quickly. Plus after you take a shower, you are clean, so the towel you use to dry off should be clean too, right?

On the other hand damp, warm towels are a nearly perfect environment for microbial growth and rarely washing your towels might lead to towels that are—well—pretty gross.

So what’s the ideal number of days to use your towel so that you’re not exposing yourself to potentially nasty bacteria, mold, and yeast after taking a shower?

We teamed up with NSF International (www.nsf.org) to find out.   Viewers from all over the country sent their towels to the NSF International laboratory in Ann Arbor, Michigan to see just how dirty they were.  In total we tested 31 towels that had been used for either 1, 7, or 14 days. In the lab, NSF International scientists conducted microbiological tests on each towel in search of the following microbes:

  • Yeast/mold — Microbes that can cause respiratory disease or magnify allergies.
  • Aerobic bacteria — Bacteria that grow in the presence of oxygen and are a common cause of clinical infection.
  • Coliforms — Bacteria of fecal origin that include E. coli.
  • E. coli bacteria — Associated with food poisoning and a common cause of urinary track infections.

What we found was surprising.  Significant numbers of bacteria were present on all of the towels we tested, including those used for only one day.  Also significant yeast microbes were present on more than half of the towels and mold was present on nearly half of the towels. Some of the towels even held significant amounts of E. coli.  

As you might expect, the test revealed that the towels tended to get dirtier the longer they were used. For example, towels used for 1 day were generally cleaner than towels used for 7 days. And towels used for 7 days were generally cleaner than the ones used for 14 days. In fact, NSF International concluded that for every seven days a towel was used, the amount of microorganisms present on the towel almost doubled.

The study also compared towels used by women to towels used by men. While the towels used by men generally contained more E. coli, the towels used by women contained more yeast microbes. For example, the E. coli count was 10x greater in towels used by men after 14 days of use compared to towels used by women over the same time frame. However, towels used by women for just one day contained 100 times more viable yeast microorganisms than towels used by men.

Using towels with the levels of E. coli found at two weeks could potentially cause a serious illness or infection if the bacteria is ingested or comes in contact with an open wound. Personally, I wouldn’t want to dry my face with one of those towels!

Based on this study, we recommend using a towel for no longer than seven days.  In fact its probably best to change your towel at least twice a week, because we found that after 1 week, while the levels of bacteria were growing, the levels of yeast and mold on the towels plateaued and you don’t really want to be rubbing those organisms all over your body either.