Sunday, July 29, 2007
Hot Water: a Good Thing
A few days ago a patient of mine mentioned in the course of her visit that her hot water heater had recently stopped working and that, as a result, she'd noticed her water supply was slightly darker than normal; was this a problem?
I told her she could be at risk for bacterial overgrowth in her water supply, due to Legionella and its propensity for colonizing water lines. To rid a system of this bacteria, it must be flushed with hot water. This is why all water heaters have a minimum recommended set temperature on them; the water in the tank must be at least 130 degrees Fahrenheit (to allow for cooling in the pipes). Legionella is a perennial problem in hospitals, since they often use nebulized water for inhaled medication treatments and to humidify high-flow oxygen. Bacteria can also colonize the plastic hosing used in ventilators, if someone is intubated and hooked up to a breathing machine. Another risk in a home water supply that isn't heated might be cryptosporidium, a small cystic parasite that can sometimes colonize water supplies and causes diarrhea in humans.
Legionella isn't just limited to hospitals; the original outbreak that gave the disease its name was related to the cooling tower in a hotel air-conditioning system. For good measure I explained that there had once been an outbreak of Legionnaire's disease that had been traced to the produce mister in a grocery store. She quickly agreed to get the water heater hooked up again.