alternative hot water and legionnaires' disease

Water Pressure: high water pressure = aerosol. Lots of tiny particles to breathe in.

Perhaps people with low water pressure have less risk? Bath is safer than shower?

Any system that mists water can broadcast bacteria into the air. I remember reading some article about a different disease caused by fungi living in water pipes - problem was cased by inhaling water during showers.

Just a thought.

frankenstoen wrote:

Any system that mists water can broadcast bacteria into the air. I remember reading some article about a different disease caused by fungi living in water pipes - problem was cased by inhaling water during showers.

For those who didn't know...
The original Legionnaires bacterium was discovered when people at an American Legion convention on an ocean liner came down with this strange unknown infection.  The source was finally tracked down to the water tanks that supplied water for the showers.  A second outbreak shortly thereafter in Los Angeles was traced to the hotel ventilation system, where Legionnaires (among other things) was found in places where moisture had condensed and stood for long periods of time.

Barry,

Excellent video!

How do you feel about the water heated by a compost pile?

Here is my five cent summary of the information gathered so far:

1)  115 degrees F is an excellent temperature for legionella bacteria to reproduce.  So turning your water heater down to this temperature is a really bad idea.  A good temperature for a hot water heater is 140 degrees F.

2)  85% of pneumonia cases are caused by legionella bacteria.

3)  many solar hot water systems make excellent legionella bacteria incubators.  When considering solar hot water designs, make sure your design mitigates legionella issues.

4)  To save energy with a hot water heater:  Use less hot water;  insulate your hot water heater; when your current water heater dies, replace it with a smaller hot water heater;  insulate your hot water pipes, so that people using a sink/shower will get hot enough water sooner; turn off your hot water heater when you leave for more than a day.

Any of this less than accurate?

I'd add for HWHTR's and your furnace to make sure the flue pipe is clear.

Make sure their is not more draft than needed. I.E. the geniues that installed/built my home has an forced draft furnace and the HWHTR is tied into the stack. This creates a draft on the HWHTR when the fan is on.

My only option is to run the furnace out the wall and let teh HWHTR draft up through the roof as designed.

I set up a HWHTR on how amny are in the home. 2 people 110' `  3 people 115'  ~ dishwasher 130' & 5 people.

It all depends on how many use teh shower in a row.

Legionella in small domestic water tanks is not a worry. Ships domestic H2O systems and air handlers have vastly different contamination issues.


Circulation of

paul wheaton wrote:
Here is my five cent summary of the information gathered so far:

1)  115 degrees F is an excellent temperature for legionella bacteria to reproduce.  So turning your water heater down to this temperature is a really bad idea.  A good temperature for a hot water heater is 140 degrees F.

2)  85% of pneumonia cases are caused by legionella bacteria.

3)  many solar hot water systems make excellent legionella bacteria incubators.  When considering solar hot water designs, make sure your design mitigates legionella issues.

4)  To save energy with a hot water heater:  Use less hot water;   insulate your hot water heater; when your current water heater dies, replace it with a smaller hot water heater;  insulate your hot water pipes, so that people using a sink/shower will get hot enough water sooner; turn off your hot water heater when you leave for more than a day.

Any of this less than accurate?

And so what is the temp of the water at the outlet?

What keeps Hot Tubs safe...the chemicals...My wood fired tube works fine..
https://permies.com/bb/index.php?topic=4051.msg38448#msg38448

ronie wrote:
And so what is the temp of the water at the outlet?

Which outlet? 

At a sink, it could be 140.    If there is concern over scalding, I would like to point out that there is also a stove in the kitchen that can easily burn a person.  It takes a teeny tiny amount of savvy to not get scalded - just as it takes a pinch of savvy to not get burned.

Plus, there are mixers that will lower the temp to 110 just outside of the water heater.  Apparently they are pretty cheap.

Any and all outlets. If the hot water heater is set at 140 then what is the temp at all outlets.

When I researched Legionella for you last year the research I read said that the main accumulation of bacteria was near the outlets.

But also I never ran across any cases of Legionella that were in a small home system. All the reported cases were in a large central hot water system..Much like  Blackpowderbill said in his post:

blackpowderbill wrote:
Legionella in small domestic water tanks is not a worry. Ships domestic H2O systems and air handlers have vastly different contamination issues.

That doesn't jive with the stuff about home solar. 

And the stuff in my head says that home stuff is a danger.  My suspicion is that there are not enough people at one time in one place to create a pattern so it is probably not properly diagnosed.

I was mainly talking about home hot water systems other than solar. So what "stuff" about home solar are you talking about?

Also what is the source that says that 85% of pneumonia is caused by Legionella?

Saw this today:

http://www.popularmechanics.com/science/health/5-places-in-your-home-that-are-breeding-superbugs#fbIndex2

The implication is that the type of shower head used might affect one's chances of infection. Smaller droplets are more likely to be inhaled.

      Concerning the woodfired hot tub. Woodfired hot tubs are less likely to have bacteria problems than are electric tubs because the water temperature goes through huge temperature swings. The bacteria which live at one temperature are unable to survive at a vastly different temperature. This is the principle behind pasteurization. Even those hot sulfur filled pools at Yellowstone contain bacteria but these are not the same brand of bacteria which come out of your well. By allowing hot tubs to cool down completely then cranking the temperature way up you create conditions which are unsuitable to any of the bacteria. All of my attempts at solar water heating have been of the batch type. If water is heated for each day's use the bacteria colony has little time for a population explosion.

Paul, Caleb, and Krista talk about hot water in this podcast: hot water podcast

They talk about legionella bacteria.

Paul talks with Ernie and Erica about rocket mass heaters in this podcast: rocket mass heater podcast

They also discuss legionella bacteria.

Muzhik McCoy wrote:

Eric wrote:
Crazy question: why not just heat water on the stove and sponge bathe?

While I can't speak for others, I can say that my daughters, darlings though they are, don't appreciate coming downstairs in the morning to see their dad naked in the kitchen touching himself.

Strange, I know, but what can you do?  Kids nowadays...

My grandmother's family had to sponge bathe when their indoor plumbing filled with mud during the Dust Bowl.
She wrote about carrying a bucket or two of hot water into the girls' private upstairs room for her cousins to bathe (and how her city cousins turned up their noses, intensely embarrassing for her as a teenager).

I would respectfully submit that as a paterfamilias, you are at least as capable of carrying a bucket of hot water someplace private, as my scrawny grandmother.
(The Little House books also described hanging a sheet or curtain in front of the fireplace while the family took turns bathing.)

(none of the above will necessarily prevent a brace of daughters from indulging in overblown embarrassment - there is probably no power in the universe that can do this, but at least you can feel confident that it is their problem and not yours.)

For those more interested in Mod Cons, I just posted a link to a SOLAR HOT WATER workshop happening this week near Anacortes, WA. Short notice I know, but SEI does these on a regular basis and it would be worth checking out what their experienced instructors have to say about safe setups for different uses.

https://permies.com/t/13945/cascadia/Workshop-Solar-Hot-Water-starts#124652


The workshop itself: www.solarenergy.org

-Erica W

Bacteria need at least three things to thrive: proper food, proper environment, proper temperature.

It seems to me if you can't remove it's micronutrients from the water and if you operate at its "thrive" temperature then you need to attack its environment while sitting stagnant. There has been several articles I have read where hospitals have used and other research done that have proven that some metals, copper in particular, kills nasties of several sorts. Here's a link if you don't believe me - copper kills bacteria and viruses-
Wouldn't it be good to make the area of containment that could hold water stagnant and at the warned temperature from copper or inbed a copper mesh in a dark holding tank? Maybe someone could do a lab test on this specific bacteria. Anyways, after this thread I'm holding my breath in all solar showers..... If you use it I guess I will make millions from intellectual property rights! lol Not!

edited P.S.- Now that I think about it, as a child we had a room humidifier that blew air through a revolving wet mesh made of woven copper. Perhaps there was their secret legionella killer and they didn't even know it. I know you may think, "it can't be that simple but, can't it sometimes?"

you could purify the water before you heat it with iodine or silver…

or give some mental prep classes and let the cold water be apart of the zen.


cut out hot water and put berms on 3 sides of every house, we could solve a lot of energy issues. Hard sell politically . going to take a nice hot shower before they cut it.

Okay, I admit I haven't read the eleventy-seven gazillion posts on this page and may be repeating someone else's posting -- BUT  -- as a 48-year (retired now!) plumbing professional, I'm here to tell you the straight skinny on Legionnaire's Disease:

This condition comes from cross-connected lines.  What happens is, water in a pipe, which is normally under pressure, is for whatever reason allowed to drop to near atmospheric pressure (like when a pipe breaks, etc.) and water from a "tainted" source is sucked into the system.  It can happen to hot or cold lines.  It all depends on the source of the break and a bunch of other factors, which can change or happen simultaneously.  

For instance, here's a scenario:  Lets say you own a home and decide to water your back yard slope.  Yesterday, you spread cow manure all over your piece of the pie to help green up the back yard, which mean, in essence, raw sewage (albeit animal waste) is on the ground around and under plants.  So, you water the slope an in the interim, something causes you to turn off your water at either the house isolation valve or the meter.  Maybe you decide to fix a leak and figure the sprinklers will just come back on when you're finished with your repair; no biggie.

OOPS -- BIGGIE!

If, perchance, your back slope is higher than the lowest fitting in your house, when the water is turned off and the pressure inside your home's plumbing system drops to zero, the elevation difference between the two, causes water sitting in a puddle around a low-lying sprinkler's opening, atop the slope to drain by gravity (siphon as it were) into the pipe and if it gets all the way to your lowest fixture, you, my friend, have cross-connected your system and exposed it to a lethal pathogen.  That's basically how it starts.

In homes built after about 1975, "anti-siphon" hose bibs as well as several other applications are required by law in an effort to halt cross-connection incidents and for the most part, have done that job quite well.  Ever hear of a "back-flow preventer"?  Same animal -- does the same job -- prevents back-flow in an otherwise closed system.

Hope that clears it up.  It has less to do with the temperature of the water in the pipe and more to do with the biological condition of that same water.

From UpToDate, an online textbook for medical professionals:

Legionnaires' disease — The reported incidence of Legionnaires' disease is approximately 1.4 to 1.8 cases per 100,000 persons in the United States, Europe, and Australia [19-21]. Within these regions, local rates range from approximately 0.4 to 5.0 cases per 100,000 persons. The highest reported incidence (5.3 cases per 100,000 persons) is in New Zealand, where L. longbeachae causes the majority of disease [22,23]. Across these regions, reported incidences are rising [19,20,23,24]. However, this rise in incidence may reflect increased awareness, improved diagnostic tests, and/or changes in reporting standards rather than a true rise in incidence.

Legionnaires' disease may be community acquired or acquired in health care facilities.

●Community-acquired pneumonia – Legionnaires' disease accounts for approximately 1 to 10 percent of cases of community-acquired pneumonia (CAP) [25-29]. CAP caused by Legionellae is most often diagnosed in hospitalized patients and can be severe. Up to 44 percent of patients have been reported to require intensive care unit admission, and the associated mortality is approximately 1 to 10 percent [19,30,31].

●Nosocomial pneumonia – The prevalence of Legionnaires' disease in patients with nosocomial pneumonia is linked to presence and concentration of legionellae in the facility's water supply [32,33]. In the United States in 2015, approximately 20 percent of cases of Legionnaires' disease were acquired in hospitals or long-term care facilities [34].

Most community acquired pneumonia is NOT from legionellae bacteria.  Doctors are advised to consider Legionnaires when a patient doesn't respond to beta lactams (like penicillin) or is particularly sick with some particular symptoms.

More from UpToDate (sorry, it's behind a paywall and a rather expensive one at that)

Legionellae are environmental organisms found in water and soil [1]. Environmental reservoirs vary among species.

L. pneumophila and most other Legionella species mainly reside in bodies of water, such as lakes, streams, and artificial water reservoirs. Within water, Legionellae can live planktonically, in biofilms, or as intracellular parasites within protozoa (eg, free-living amoeba and ciliates) [6]. Replication within protozoa protects the organism from temperature shifts, pH changes, and nutrient-poor environments. Additional factors that promote growth in water include warm temperatures (25 to 42°C), stagnation, and sedimentation.

Legionella bacteria are typically transmitted to humans via inhalation of aerosols derived from water or soil [7,14]. The infectious dose for humans has not been precisely quantified but is likely high, requiring >1000 organisms to cause infection [1,15].

Contamination of water sources with concentrations of Legionella high enough to cause human infection can occur when changes in water flow or pressure disrupt biofilms, releasing large amounts of bacteria into the surrounding water [1]. Legionella's ability to grow intracellularly within free-living amoeba may also facilitate transmission from either water or soil [1,16,17]. A single infected amoebal cyst may contain thousands of Legionella bacteria and, if aerosolized, could easily deliver an infectious dose.

Laboratory and person-to-person transmission generally do not occur, likely due to the high infectious dose. However, a single case of possible person-to-person transmission has been reported [18].

History:

Legionella bacteria were first identified as a result of the investigation of an outbreak of severe pneumonia among attendees at an American Legion convention in 1976 [37-39]. The initial outbreak involved 182 persons and was linked to contamination of the air conditioning system at the hotel where the convention was held.

Subsequently, Legionella has been identified as a common cause of waterborne disease outbreaks. During 2015, there were 54 reported Legionnaires' disease outbreaks in Europe alone, involving 559 cases from 11 countries [20]. While the largest of these outbreaks involved 304 persons, most affected <10 persons. Large outbreaks are often associated with contaminated industrial cooling towers or water systems that supply communities or facilities such as hospitals, hotels, cruise ships, or apartment buildings [40-46].

As examples, contaminated cooling towers were responsible for an outbreak at the Melbourne Aquarium that involved 125 visitors [44]. Seventy-six percent of patients required hospitalization, and the case-fatality rate was 3 percent. In an outbreak at a Dutch flower show, 188 visitors became ill after exposure to a contaminated whirlpool spa in the exhibition hall [47]. However, contamination of any water source can also lead to infection.

Sources of infection:

Most Legionella infections are associated with exposure to contaminated manmade water reservoirs. Reported sources of infection are diverse and include showers [58], pools [59], hot tubs [60], aquariums [44], fountains [61], birthing pools [62,63], drinking water systems [14,52], air conditioning systems and cooling towers [64,65], and other water collection systems [66,67]. Natural water systems, such as rivers and streams, are less common sources of infection [68].

I'm happy to track down specific references for those who want them.  (Give me the number and a couple words before it and I'll easily get you the abstract.)

Julia,

I suspect that this is an american source?  I wonder if an english source would have conflicting information?  Such conflicting information would explain why american stuff says "set your hot water heater to 110" and other countries insist that it needs to be set much higher to prevent legionella stuff.

I was curious to see what the local (Brazil) literature has to say on this, since it is normal to have a water reservoir under your roof (which often stays warm all day) and NO water heaters, in many cases, and yet we rarely hear about Legionella. The general advice is to clean these reservoirs yearly but not necessarily for legionella, but rather for other diseases. Air conditioners (including car AC units), cooling towers for large air conditioning installations, and humidifiers are considered much more dangerous, and Legionnaire's is considered a disease that attacks only the immunocompromised, elderly, etc.
However, some researchers believe that legionella is definitely a major problem and it simply isn't considered when doctors are diagnosing pneumonia. I suspect that is more likely- the richer people have gas heating units for their showers, while the poorer people who don't heat their water also get public health care which may be more focused on putting out fires than looking for specific bacterial causes.

In order to avoid issues, i modeled the diy of our dhw system from this appliance. Out of my price range and not easy had.

https://www.rotex-heating.com/products/thermal-store.html

paul wheaton wrote:Julia,

I suspect that this is an american source?  I wonder if an english source would have conflicting information?  Such conflicting information would explain why american stuff says "set your hot water heater to 110" and other countries insist that it needs to be set much higher to prevent legionella stuff.

UpToDate is primarily American.  Looking through the authors, most are from American institutions like Harvard or the Mayo Clinic.  However, there is a generous sprinkling of contributors from all over the world: England, Scotland, Egypt, Australia, New Zealand, Canada, Italy, etc  

I think the advice from UpToDate is to keep water heaters hot.  It's not really a source of advice for home owners.  

My main message here is that Legionellae, while significant, is not the most common reason for pneumonia (that's generally streptococcus pneumoniae, if you leave out the viruses).  

Legionellae is responsible for 1% to 10% of community acquired pneumonia in the United States, Europe and Australia.  It's bad news, for sure - it leads to much higher rates of ICU admission and death than with more common forms of pneumonia.  But the 85% figure - I don't know where that came from, and wherever that was, it should go back there.

It has been a long time since I did my research for this.  

I wish to propose that both are correct.  I propose that legionellae opens the door for streptococcus pneumoniae.  In other words, eliminating legionellae would prevent 85% of pneumonia.

You could propose that, but the description of legionellae in UpToDate is of a bacteria that causes such a strong immune response, the patient's own immune response may cause more damage than the infection.  

(Chicken pox is another illness like this -it's why people who are older when they get chicken pox get sicker.)  

Anyway, a bacteria that operates like that is highly unlikely to be a silent background contributor to pneumonia.

Testing for legionella is almost universally done when a bunch of people get the same symptoms at the same time.  It is almost never done when one person gets pneumonia.  It is as if the pneumonia comes from the pneumonia fairy -  TING!  You get pneumonia!

Ever since sharing this, I have heard from a dozen different people that suffered from regular bouts of pneumonia and they caught wind of my concerns and found that, yes, their hot water heater was set to 110.  So they turned it up to 140 and the problems went away.  

Jocelyn's grandmother was in the hospital AGAIN for pneumonia and so Jocelyn's uncle went and checked on the water heater.  110.  He turned it up to 140 and no more pneumonia.  

Does this prove that I am right?   No!  Does it prove that it is a path worth considering?  Fuck, yes!  Is it possible that my 85% number can be proven, in time, to be rock solid?  YES!  


And now for the real question:   Dr. Winter ....   I know, for a fact that you are a practicing physician.   Which is why you have access to such expensive information.  I have presented my case to you.  You wish for me to stop saying "85%" because this number has not been supported by the research that you have access to.  But here is the most important question:  what temperature is your water heater set to?  If you turn it down to 110, you will save a trivial amount of energy.  The energy savings are real.  

I think the stories of people who keep getting pneumonia until they turn up their water heater are compelling, and you should have THAT in your book.  

I wish for you to stop saying "85%" because that is a number you pulled out of your butt.  That is a stinky number.  Don't use it.

It's not crazy to say that you surmise many cases of pneumonia are predicated by legionellae.  It takes inhaling a thousand of them to get full on legionnaire's disease, but maybe if you inhale 50 of them it irritates your lungs and sets you up for strep pneumoniae.  (Please don't quote me on this - I am using my imagination here.) My professional sources say that legionellae aren't killed by the usual antibiotics, so I do feel pretty confident that the majority of pneumonia cases that I treat are NOT (primarily) from legionellae, because they DO respond to the usual antibiotics.

The other thing to consider with water heater temps is scalding risk.  From https://www.mrrooter.com/about/blog/2018/april/what-temperature-should-a-hot-water-heater-be-se/

What Temperature Should a Hot Water Heater Be Set At?
Apr 19, 2018

What Temperature Should a Hot Water Heater Be Set At?

Your water heater accounts for about 18 percent of your home’s energy bill. If your water heater is set too high, you will be paying the price in your energy bill each month. On the flip side, if your water heater is set too low your water may not get hot enough (short showers), or worse, be at risk of growing bacteria. Don’t set your water heater to anything below 120 degrees, as diseases can develop in the stagnant water inside the water heater, particularly Legionella, which is quite dangerous.

So, what is the best temperature range for your water heater? The EPA recommends 120 degrees because it’s hot enough to keep diseases at bay, it’s not hot enough to cause scalding, it will supply enough hot water for most small families and is relatively energy-efficient. However, the best setting for you could vary based on a few factors.
Factors That Affect Hot Water Temperature Setting

These factors are not affected by the kind of plumbing you have (PEX, PVC or copper), how the water is heated (gas or electric) or even if you a tankless hot water heater.

Homeowners with a dishwasher that does not pre-heat the water may want to set their water heater to 140 degrees.
Elderly homeowners or those with small children may want to keep the temperature at 120 degrees. According to BabyCenter.com, “It takes just two seconds for a child to receive third-degree burns from water that is 150 degrees and five seconds if it is 140 degrees, the temperatures at which hot water heaters often leave the factory.”
Homes with occupants that have a suppressed immune system or respiratory disease should keep the hot water set to 140 degrees.
In general, many who live alone aim for a lower temperature in the acceptable range since demand for hot water is less and it saves money. Many who live in large household aim for a higher temperature to accommodate increased demand for hot water.
If you want to save money, every 10 degrees you turn down the water tank thermometer, you save 3 to 5 percent on your energy bill.

Still undecided? Set it at 120 degrees and increase the temperature in small increments until you find the perfect shower temperature.

Scalding risk has entirely been solved by thermostatically controlled mixing valves:



https://amzn.to/2V6GvXy


I have presented my case.   I have a long list of reasons why I stand by "85%".  And I presented a few of the reasons why I dismiss

Legionellae is responsible for 1% to 10% of community acquired pneumonia in the United States, Europe and Australia.

and choose "85% of **ALL** pneumonia."

The bottom line is that there are known issues and there are mysteries.  And I suspect that you will confirm that nearly all doctors will treat pneumonia without much consideration for how the patient acquired pneumonia.  It is even possible that more than 85% of the cases of pneumonia were caused by legionella, but the cause is typically skipped over.  

There are massive areas of physiology and how we interact with the other life forms on this planet that have not yet been sorted out.  

I authentically believe that the 85% number is solid.  And I would like people who have had recurring pneumonia to report, here in this thread, the temperature their water heater is set to.  This is where science begins:  present a question and begin collecting anecdotal data.


Dr. Winter, I ask again:  what is the current temperature setting for the hot water heater in your home?  

This site about Legionella is from research experts in the field http://legionella.org/about-the-disease/what-is-legionnaires-disease/how-is-the-disease-contracted/

They state that contrary to popular thought, Legionella is mainly contracted by aspiration rather than by inhalation, and mechanisms that protect against aspiration are more commonly defective in smokers.

So, to avoid infection, apart from not smoking or having respiratory/immune compromised states etc, you need to boil the water before you drink it.
Could increasing the temperature of the HWC to 140F reduce respiratory diseases?  Who knows?  But if you need to open up your tank to consciously alter the thermostat on your HWC, maybe you also alter some other health related behaviors.   Anyway, it's an interesting anecdote.

paul wheaton wrote: I suspect that you will confirm that nearly all doctors will treat pneumonia without much consideration for how the patient acquired pneumonia.  It is even possible that more than 85% of the cases of pneumonia were caused by legionella, but the cause is typically skipped over.  

Legionellae is not sensitive to the first line antibiotics used for community acquired pneumonia, which is why my sources advise MDs to consider legionellae when a patient is very sick and doesn't get better with the usual treatment.

I authentically believe that the 85% number is solid.  And I would like people who have had recurring pneumonia to report, here in this thread, the temperature their water heater is set to.  This is where science begins:  present a question and begin collecting anecdotal data.

It's good to believe things.  It's . . . . kind of special to assign specific numbers to your beliefs.  This is the fallacy of false precision ( https://en.wikipedia.org/wiki/False_precision )

Dr. Winter, I ask again:  what is the current temperature setting for the hot water heater in your home?  

This was harder to find out than I thought it would be.  I asked my husband, but he didn't know.  We went down into the basement and found that our hot water heater is set about halfway between "WARM" and "HOT."  So, I'm not sure what the current temperature setting is.  I could run the hot water for a long time and then measure the temperature at the kitchen sink, but that wouldn't really be correct.  Also, that seems wasteful. [Addendum: DH measured it at 137F]  Nobody in our house has had pneumonia, at least not since we've moved to this house.  (I think not ever.)

Here's more on the fallacy of false precision, from the link above:

Wikipedia wrote:False precision (also called overprecision, fake precision, misplaced precision and spurious precision) occurs when numerical data are presented in a manner that implies better precision than is justified; since precision is a limit to accuracy, this often leads to overconfidence in the accuracy, named precision bias.

Pointing out the fallacy of an argument is, itself, a fallacy.  In other words, if you point out a fallacy in an argument it does not prove that you are correct.  

Next up, half of the known fallacies are things where there can be weight to that argument, but that argument alone in no way proves the position.  It is the inability to prove the position that makes it a fallacy.  

Geoff Lawton is keen on swales

This is an "appeal to authority fallacy".   It is definitely a fallacy, but, depending on the level of respect the debaters have for Geoff, it does have weight and would be of influence in making decisions.


And, finally, saying "it is 85%" falls into false precision.  But saying "I think it is 85%" is 100% perfectly true with absolute fact sauce smothered on the top.  And if anybody suggests that it is anything less than true is a twisted liar infested with the disease of all the evils who is making a feeble attempt to claim that they have the ability to read to minds and failing miserably.  This is the mighty power of properly qualified statement such as starting the statement with "I think".

Julia, did I ever tell you about the book I wrote about fallacy?  About 250 pages now, but it isn't quite ready for publication.  Very serious - I really do have this book collecting dust on my computer.

So let's take a really close look at my qualifiers:

Here is my five cent summary of the information gathered so far: 85% of pneumonia cases are caused by legionella bacteria.

I propose that legionellae opens the door for streptococcus pneumoniae.  In other words, eliminating legionellae would prevent 85% of pneumonia.

Does this prove that I am right?   No!  Does it prove that it is a path worth considering?  Fuck, yes!  Is it possible that my 85% number can be proven, in time, to be rock solid?  YES!

I have presented my case.   I have a long list of reasons why I stand by "85%".  And I presented a few of the reasons why I dismiss

Legionellae is responsible for 1% to 10% of community acquired pneumonia in the United States, Europe and Australia.

and choose "85% of **ALL** pneumonia."  

They look properly qualified to me.

The important thing is that I am allowed to have an opinion.  And I am allowed to have super wack-a-doodle opinions.   And my opinions are immune to claims of fallacy, because I am not trying to win a debate.  I am trying to share what is in my head and fish for similar (or even contrary) information.  

Therefore, the fact that you choose to call "fallacy" does prove that you see this as a debate, but even worse, it proves that your argument is weak.  Because if your argument was strong, you would not feel the urge to point out fallacy.  

As usual, unraveling fallacy takes ten to twenty times longer.

We have some case reports of people with solar hot water systems getting Legionellosis but as typical with these cases they had pre-existing conditions.  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4898996/

We know that influenza typically kills because people develop nasty secondary bacterial infections.  So, the idea of something else preparing the way for Legionella has a precedent.  But there is a biological implausibility to me for a bacterium to gain sufficient hold to lower the immune defences, to then let another bacterium gain hold causing pneumonia, and the Legionella to then disappear when the patient is in even a more compromised state without leaving any serological evidence.  So, you'd have to propose a new mode of pneumonia causation with no microbiological evidence to support the thesis.

To my mind compost, potting mixes etc are a way more important vector for legionella.  I see reports in the newspapers regarding this, and have one colleague who nearly died from working with potting mix.  Now, if you're heating your water with compost I guess that even more increases your risk!

paul wheaton wrote:So let's take a really close look at my qualifiers:

Yes, let's do that!

Here is my five cent summary of the information gathered so far: 85% of pneumonia cases are caused by legionella bacteria.

I feel that this statement is not properly qualified.  It says "My summary is: 85% are caused...."  Not "After reviewing the information, I think that 85% of cases could be caused by  . . "

I propose that legionellae opens the door for streptococcus pneumoniae.  In other words, eliminating legionellae would prevent 85% of pneumonia.

I feel that this statement is not properly qualified.  It says "I propose this theory.  In other words, eliminating legionellae would prevent 85%"  Not "I propose this theory.   If I am right, then eliminating legionellae could prevent 85% . . . "

Does this prove that I am right?   No!  Does it prove that it is a path worth considering?  Fuck, yes!  Is it possible that my 85% number can be proven, in time, to be rock solid?  YES!

OK, the above statement is properly qualified.

I have presented my case.   I have a long list of reasons why I stand by "85%".  And I presented a few of the reasons why I dismiss

Legionellae is responsible for 1% to 10% of community acquired pneumonia in the United States, Europe and Australia.

and choose "85% of **ALL** pneumonia."  

I'm not impressed by this statement, but it's not surprising.  I'm rejecting multiple of your reasons.

They look properly qualified to me.

The important thing is that I am allowed to have an opinion.  And I am allowed to have super wack-a-doodle opinions.   And my opinions are immune to claims of fallacy, because I am not trying to win a debate.  I am trying to share what is in my head and fish for similar (or even contrary) information.  

You are certainly allowed to have an opinion.  When you state your opinion using artificially specific numbers like "85%" (and leave out the qualifiers that make it obvious it is just your opinion) I will point at your statement and say "fallacy."  

I've gotten no data about where the number comes from other than your gestalt sort of sense of how things are.  AFAIK, you have a feeling.  It's a strong feeling, and it's based on many things, and you think in numbers far, far more than the average bear, so your impression comes out as a number.  In general, this is cool, and here on permies, is totally cool.  The only reason I've engaged in this debate (not my favorite activity) is because you are writing a book and I want it to reach millions.  I want it to be as awesome as possible.  Stinky bum-derived numbers do not help the cause.

Therefore, the fact that you choose to call "fallacy" does prove that you see this as a debate, but even worse, it proves that your argument is weak.  Because if your argument was strong, you would not feel the urge to point out fallacy.  

Nah.  I calls 'em like I sees 'em.

As usual, unraveling fallacy takes ten to twenty times longer.

I'm with you on that!

Other data points.  

In NZ you can't legally buy a hot water cylinder that allows you to turn the thermostat below 60 deg C.

My solar hot water controller (RESOL Deltasol BX) which is about 8-9 years old now, has a disinfection mode.  It protects the upper zone of the HWC against Legionella in the event the evacuated tubes don't heat the water up sufficiently. Mine was set off which was the factory default.  I've enabled it so that if at 6 pm the HWC is not at 60C it will raise it to that temperature for an hour.

Graham Chiu wrote:In NZ you can't legally buy a hot water cylinder that allows you to turn the thermostat below 60 deg C.

For the metric impaired, 60 C is 140 F, which is apparently what my hot water heater is set to, since it comes out the kitchen tap at 137 F.

And people still get community acquired pneumonia.  As for incidence/prevalence, I have no idea.

> community acquired...

That means "nobody knows how it was acquired...". "But they were part of a group of people in the recent past".

Have I got the right?


Rufus