I EXPLAINED HOW I believe I contracted Legionnaires' disease in my May column ( A matter of grave concern, part 3). What I didn't explain was the good news/bad news scenario. The good news is that there are no known cases of a person ever having contracted the disease twice within a lifetime. The bad news is that once exposed, your lungs suffer a serious setback that requires a long time from which to recover and can have long-term impact on your ability to breathe.
Here it is, almost six months post treatment, and my lung capacity is still severely diminished. And even the slightest head or chest cold feels as if it could slip into pneumonia at any time.
Back at the doctor's office, I asked my physician why she thought that the incidence of reporting Legionnaires' disease was so low, and why it is that the U.S. Centers for Disease Control and Prevention stated that it is probably one of the most misdiagnosed diseases in the world. She said that my exposure is a typical example. I came in, was diagnosed with bacterial pneumonia and was given broad-spectrum antibiotics to cure me. Who cares where you got it from? Just treat the disease and move on.
The sad thing, she said, is that elderly people die from this disease all the time, and it goes undiagnosed due to their age.
"The ol' boy was 94. What'd he die from? Pneumonia? Well, he lived a good long life."
Doctors don't bother determining where the pneumonia came from unless it occurs as an identifiable " outbreak" pattern. Then all hell breaks loose, the source is discovered, treated and maintained, and Legionella is found to be the root cause.
Elderly people die from this disease all the time.
So here we are, a country with the greatest system for health protection and building code protection in the free world, that allows people to be exposed to this serious disease on a daily basis. How can that be?
In our "system" of protection, if it is thought that a condition could cause an unhealthy situation, it is generally addressed at the grassroots level of the building codes. Our potable water is protected by this code through air-gap and backflow prevention requirements. These measures avoid contaminants being introduced into the potable water system from back-siphonage. The incoming water is protected by the municipal water system, when and where applicable.
Legionella pneumophila is one of many omnipresent bacteria that the EPA does not address because, other than scald sanitization, there really are no approved pre-treatment methods. It's known that it is there, and it is presumed that the end user will address its presence at the point of use, using proven methods of bacterial control — that accepted method being heating the water higher than 140°F. In other words, keep the water hot enough to suppress bacterial amplification.
Sounds reasonable enough ...
Except that our code allows the use of open potable water combination heating systems with the potential of being bacterial amplifiers. How's that, you ask? The code has an approval for these systems whereby the water in the panel distribution system is "refreshed" or replaced by incoming water during every domestic hot water use. Shouldn't that take care of any "ideal" bacterial amplification situation? Not necessarily. If the heating distribution system is exactly as has been described to the code authorities, then, yes, it will flush fresh water into the heat distribution system with each use.
But simply introducing fresh water into the system is not adequate protection. Remember the things necessary for amplification? Water, warmth, food, proper pH and oxygen. This open supply only serves to replenish the bacteria with four of the five things necessary to guarantee survival. The fifth component, that being heat, is provided by the house itself, and enhanced by the water heater, hence a perfect environment for bacterial amplification. The problem is not necessarily the water heater itself as much as it is the tubing within the radiant panel. If the heater is maintained above 120°, the bacteria may be present, but not in enough of a concentration to allow a major infection to occur.
Remember, we are all exposed to the bacteria on a daily basis. It's a matter of how much exposure, under certain conditions during certain health conditions that can cause an infection. And isn't this what the code is supposed to protect us from?
I have had contractors tell me that their method of protection is to have a circulator come on once a day to move water between the heat source and the distribution media. First off, anything that depends on a mechanical device for bottom-line protection is only as reliable as that critical mechanical component and, in my experience, pumps and circulators fail on a regular basis.
Secondly, under the current code-approved " flushing" scenario, if the home has more than one zone of heating, which is rather common in my experience, all zone valves would have to be open at the same time to guarantee complete flushing of the system anyway which, based on my previous observation, is a rather moot point anyway.
If no one is home for an extended period of time (summer vacation) to use the water, the water lying in the radiant panel is in an ideal bacterial amplification situation. When the occupants of the home get back from their vacation, fresh off the pay-per-ride germ exposure tube (jet airplane), they are guaranteed exposure to a higher than normal concentration of the bacteria. To me, this does not spell protection, this spells guaranteed direct exposure to a deadly disease.
Tune in next month as we come up with ways to fix this problem. Until then, make sure you have your water heater turned above 120° to avoid bacterial amplification. And Happy Bacteria Reducing Hydronicing!
Mark Eatherton is a Denver-based hydronics contractor. He can be reached via e-mail at [email protected] or by phone at 303/778-7772.