Sunday, October 26, 2008

The Case For Very Hot Water

Science News: "For years, conservation advocates have told consumers to turn down the thermostat on their hot-water heaters — largely to save energy, but also to avoid scalding showers and baths. At least for some people, however, this green tactic could prove dangerous, new studies indicate.
“The number one cause of waterborne disease outbreaks in the United States,” says environmental engineer Marc Edwards, “is not contaminants leaving the water treatment plant (we do a good job of killing those). It’s the pathogens that grow in home water heaters.”
Last weekend, seven reporters attending the Society of Environmental Journalists annual meeting toured Edwards’ lab of at Virginia Tech, in Blacksburg — and were treated to some sobering information about water quality. Like that in water heaters.
On its website, the Department of Energy notes that, “Although some manufacturers set water heater thermostats at 140 ºF, most households usually only require them set at 120 ºF.” For each 10º drop in temperature, consumers can expect to see a three to five percent savings on energy use. Moreover, DOE points out, setting that thermostat to 120º could extend the heater’s lifetime by slowing the buildup of minerals and corrosion within it.
What DOE and other energy-conservation sites don’t point out is that 140 ºF will kill a number of potentially lethal waterborne organisms, like the ones responsible for Legionnaire’s disease and NTM, short for nontuberculous mycobacterial infections. Indeed, 120º provides a nurturing environment for such toxic microbes
Owing to lead-poisoning concerns, people should never drink hot tap water. That’s why the primary route to respiratory disease from these germs comes through inhalation of the steam associated with showering or hot tubs. Infections due to these home-grown germs are estimated to kill 3,000 to 12,000 Americans annually, Edwards says.
How come we haven’t heard about this? Mistaken for flu, many cases remain off the radar screen, he says. But check the web and you’ll find Edwards wasn’t exaggerating about a growing link between hot-water heaters and disease. A few months ago in the Journal of Water and Health, Joseph O. Falkinham III, also at Virginia Tech, and his colleagues reported on a shower link to NTM in a 41-year-old New York City physician."

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