Some Like It Hot


Natalie Abram

Consider this statement: Hot water has the ability to scald human skin; so, it also must kill anything inside it.  Wrong!  One of the biggest misconceptions about microbes is that warm/hot water is unsuitable for them.  We are taught that boiling water will ‘kill’ the bacteria inside.  Surprisingly, these extreme environments can contain unique microorganisms that thrive with the hotter temperatures.  

One bacterium that loves hot water is Legionella.  When the bacterium becomes aerosolized, taking the breaths inside a shower has the potential to spread into the lungs.  This infection can lead to Pneumonia, Legionnaires’ Disease or Pontiac Fever1.  Although they are 100% treatable, it is difficult to pinpoint the multitude of symptoms for this specific bacterial infection without invasive tests and x-rays.  Once confirmed, antibiotics will be prescribed.  But the ultimate question, how did the person contract the bacterium?  Did they travel?  Use a hot tub?  Play in a water fountain?  Or, even take a hot shower at home?

Legionella is an opportunistic microbe and flourishes anywhere it can find freshwater and the right water temperature.  If present in a biofilm, Legionella can live symbiotically with algae, fungi, protozoa like Amoeba and even other bacteria.2 [Biofilms are that slimy feeling when you touch the inside of a pipe or a dog water bowl.]  One common household place the bacterium has the potential to lurk, is inside the hot water tank for the household hot water heater.  All homes use the water heater for bathing, washing and sanitation.  Hot water tanks hold limited quantities of water and maintain the constant water temperature preset by the owner until it is dispersed into the pipes and then is refilled.  Very rarely are the hot water tanks drained and cleaned.  If Legionella makes its way into the household tank, the combination of frequent new water flow and the cozy 120˚F to 140˚F temperature range is the perfect habitat for an entire colony to exist.  Although any water temperature above 140˚ can kill the bacterium, the higher temperatures can be risky for children and the elderly with accidental severe scalding.

Preventing Legionella

Since standard water treatment do not eliminate this particular bacterium; it is not recommended to add biocides into the water tank for additional sanitation because that water can be ingested during teeth brushing, cooking or even drinking.  Chlorine loses its effectiveness in warm water and cannot be an additional disinfectant.  If the bacterium is found in the household, the solution then becomes a full tank cleaning and draining.  Professional plumbing services can be called upon to drain and sanitize your water heater.  Some water tanks can be fitted with additional filtration devices or ionizers.  One study has shown that the combination of copper and silver with ionization can control the bacteria.3   The presence of these metal ions prevented the bacterium from adhering to the inside of the pipes.  Another study shows that ozonation can reduce microbial contamination.4

Another ideal option is replacing your water heater altogether.  Tankless water heater replacements are on the rise.  They are becoming more preferred over the traditional water heater since it is a space saver and more energy efficient.  The typical wall-mounted device heats the water directly in the designated hot water pipes as needed.  The water is not held in a tank, so it reduces the possibility of Legionella coming from your water heater.        


Some communities offer water testing for Legionella, if outbreaks are a common occurrence.  So please contact your local water authorities for more details.  There are guidelines and resources to call upon for additional information.5   At the water treatment professional level, state of the art testing kits will soon be on the market.6  


Tankless Water heaters are the preferred domestic home solution for sustainable hot water, energy savings and Legionella prevention.