Tuesday, March 29, 2011

Is your hot water hot enough?

There's an interesting paper in the March issue of Emerging Infectious Diseases that examines water cultures from homes of patients with nontuberculous mycobacterial infections (full text here). This paper caught my eye because it's our perception at VCU that we're seeing more patients with pulmonary atypical mycobacterial infections. Curiously, we rarely see Legionella, another waterborne pathogen.

In this study, water samples were obtained from 31 NTM-infected patients' homes from across the US. 59% of the homes had NTMs found in the water, and 46% had matching species. Of note, patients whose hot water temperature was <125° were two-fold more likely to have contaminated water than those whose water was >130°. The author recommends that patients at risk of NTM infections (slender elderly persons and cystic fibrosis heterozygotes), crank up the heat on their hot water tanks.


  1. Thanks for finding this article. I had skipped right over it. I wonder if this is a downside to the environmental recommendations that tell us to turn the temp down on our water heaters? Strangely, we just turned our tank above 125 for the first time in 7 years since we felt our kids would just move if the water is too hot. Been nice to have clean dishes. I wonder if tankless heaters are any more "hygenic"?

  2. The author points out that the time the water is heated is also important, which was a bit disturbing, since we switched to a tankless heater last month. Though at least there's no standing water, like there would be with a tank. So I guess if my wife or I get NTM, we can blame it on being green.

  3. In the same way low flow automatic eye faucets increase the risk of biofilm, just have to find someone who can fight green issues with green solutions.