Legionnaires Disease Curtailed by Removing Contact With Air???

D107

A friend involved in the energy field today told me that he was advised that making sure that the water in a hot water tank has no exposure to air will obviate the need to keep water temps at 140. I've never heard this at all from any source on the subject, certainly not on this site, unless I've missed it. He has an indirect with an air valve on top, something else I've never heard of. This just doesn't sound right at all. Also says that the same effect can be achieved by flushing the emergency relief valve.

Gordy

How much air does a water heater tank, and associated piping get?

D107

HO here, have no idea.

Gordy

Your post says no air kills legionaries.

D107

Just looking for a clear answer on this if there is one. This person keeps their indirect at 110 degrees and would seem to be putting himself at risk. I guess the theory is that the valve is supposed to help remove air from the system. But the premise that removing air will prevent the bacteria growth is news to me.

Jamie Hall

Most hot water heaters -- if not all -- have no air in them anyway. That said, may I respectfully point out to your friend that one of the most fruitful places for Legionnaires' disease bacteria to thrive is in... cooling towers. Where there is plenty of air.

Which would seem to contradict his theory...

Canucker

How does he keep the oxygen out of the water when it's being refreshed everytime a hot water tap is opened?

D107

@Jamie yes, cooling towers, which is in fact where I believe the disease was first contracted at the Legionnaires Convention. He's very aware of that and uses that to support his theory that, 'yes, the water towers had access to air and therefore caused the disease' but believes if he can remove access to air in his tank then he can lower his water temp settings and not worry about it.
Since Legionella is described as an aerobic bacteria, and there is no air in hot water systems, how does it grow at all there?

hot_rod

Air is always replenished anytime cold flows into the tank, along with other dissolved gasses, O2 and CO2.

Amtrol Engineering Handbook claims 'the amount of air in solution in a city water main is 2% of water volume. Based on a study of 5 water departments.

Elevated temperature or chemical treatment are the agreed upon solutions.

Also contact time varies. At 140F 1 hour. I've heard at 160F, 15 minute exposure is sufficient.

Many public buildings are looking into best options for potential legionella control.

Jamie Hall

There's plenty of dissolved oxygen in the water for the little buggers to grow. They don't need air, they need oxygen.

At 110 -- which is about the optimum temperature for bacterial growth -- your friend is just asking for trouble. Don't take a shower in his house.

ChrisJ

After reading this thread my WH is still set to 140F.



I mean, not to mention 140F cleans dishes and pans a whole lot better than 110F. Even if 110F was safe, there's no way I'd run it that cool, I don't even like 120F!

Rich_49

https://www.cdc.gov/legionella/about/prevention.html

https://en.wikipedia.org/wiki/Legionella#Molecular_biology


Curious as to what you mean by the energy field ?
Energy geeks or green folks have a large problem with using any resource . I once had a gentleman from Vermont tell me that we would do anything to sell and install more equipment and that we were fear mongering about this very subject .

I do believe your friend has been misinformed and could be at risk of contracting one of the 50 species or 70 sero groups that have been identified to date .

D107

Thanks very much for this great feedback. As many might know, this subject has been dealt with in depth on this site, notably by Mssrs Rohr, Yates and Eatherton and many others. Our hwh and that at the family house has been set to 140 since I read those threads years ago. There is so much info --or should I say opinions--floating out there these days that it can be easy to be misled by a well-meaning professional who carelessly advises a client based on what they have heard but not verified. It appears to me that what I'm being told here is that installing an air vent --really for use in boilers--at the top of a domestic water heater cannot remove the oxygen from the water that can nurture the bacteria at the temperatures discussed.

Gordy

If you go to a legitimate legionella educational site that method of eradicating is not even mentioned. Read up on it, and get back to your friend, and tell him he is wrong. You'll be doing him, and his family a service.

KC_Jones

I work with people very close to this issue. It's about money. Nobody wants to admit the problem because then they have to pay. Safety (in my opinion and what is see) is the least of the concerns of the people setting standards on this issue.

The people I work with want this dealt with at the source, namely the water. The others want it dealt with after the fact meaning manufacturers of equipment susceptible to rapid growth of the little buggers.

Either way we (tax payers) are footing the bill. If I'm paying I want it dealt with as early in the process as possible.

Gordy

https://en.m.wikipedia.org/wiki/Legionella#Legionella_control

Larry Weingarten

Hello, Instead of guessing about it, why not test his water periodically? Personally, I think 130F is the minimum temp to keep stored water if everyone in the household is healthy and not too old or young.

Yours, Larry

D107

@Larry, that's an interesting idea. From what I've seen the process seems a bit involved. However the science behind the need to treat with high water temps or chemical additives seems so strong that one possible chance negative testing result shouldn't be construed to justify someone ignoring that preponderance of evidence.

D107

The response I've received from my friend and others is that the water supply is already chlorinated which should handle Legionella; and that 'Ashrae Guideline 12-2000 (for commercial buildings) says that 140 degrees is only recommended for high-risk type occupants in hospitals, healthcare, nursing homes, etc. Storage at 120deg is recommended for all other cases.' I don't have the knowledge to answer this, except to say that perhaps that guideline was originally written more information on Legionella cases have come to light. I'm sure most of us have lived our lives having 120deg heated water without negative consequences, but the level of dangerous bacteria out there may be changing all the time.

Gordy

Chlorination in city water supplies is not enough.

Yes people that are young, and elderly, or those with weak immune systems are more suseptable. Will you know when that is? A few on here can confirm they have contracted it, and some people I know personally have also. In good general health, but beaten down by short illness, and or exhaustion.

I would rather be safe then wait, and see if my immune system has weakened to the point I'm susceptible. There is to elevated tank temps with a mixing valve for anti scald to extend usage also.

So your friend has no comment on using the lack of air to eradicate legionella? His response is as you noted?

Jamie Hall

120 (or even 110) is quite appropriate -- at the tap. The reason is to avoid, or at least reduce scalding as a problem, particularly for children or older people. Quite valid. I'd agree. However...

You can achieve that with a mixing valve quite easily, and still run your water heater at 140, to avoid any possible bacteria problems.

As to the chlorination takes care of the problem. Well, yes, if you have a chlorine residual which is adequate, it will. Have you tested the chlorine residual in your system? Or... perhaps you are like many of our more rural, but overlooked, folks, who have a well -- and thus no chlorination.

Just to add to the mix here... activated carbon filters remove chlorine and disinfecting chloramines. One of the things they are sold for, and one of the reasons people buy them. They are also about as close to an ideal bacterial and fungal growth medium as can be found in a water system. If you have one, I hope you change the activated carbon often...

D107

This is very helpful, thank you. Personally I wouldn't have faith that the chlorine in a municipal system would cover the bacteria risk. A number of scholarly articles I have uncovered definitely raise the question of the effectiveness of municipally chlorinated water being an adequate protection. As for any standby losses due to the raised hot water temps at the tank--which I've seen estimated at as low as $12 a year--that would seem to be a small price to pay for the added safety. This issue will continue to be debated amongst my friend and others; my hope is that along the way we'll all be more educated.

Canucker

The chlorine in the water treatment system doesn't eliminate all the bacteria. They don't test for zero, it's below an acceptable range when it leaves the facility. Provided you don't give it an environment to grow in, you'll be safe. If I remember correctly, the amount of chlorine needed to completely elimate it would have a detrimental effect on our plumbing systems as it would leave the free chlorine level very high.

Jamie Hall

Canucker said:

The chlorine in the water treatment system doesn't eliminate all the bacteria. They don't test for zero, it's below an acceptable range when it leaves the facility. Provided you don't give it an environment to grow in, you'll be safe. If I remember correctly, the amount of chlorine needed to completely elimate it would have a detrimental effect on our plumbing systems as it would leave the free chlorine level very high.

Yea verily. When the water leaves the plant, the chlorine residual is adequate, and the bacteria count is very low indeed. However, the chlorine residual tends to disappear as you wander around the distribution system. The objective of the exercise is to always have at least a little everywhere in the system, but reality has a way of striking... and if you raised the chlorine dose high enough to ensure that you always have enough residual everywhere at all times, the customers would scream about the chlorine.

Rich_49

EPA tested municipal water systems a couple years ago and found that 50%+ contained the legionella Pneumophila bacteria .

The maximum contaminant level goal that EPA has set forth specifically for this bacteria is ZERO .

https://www.epa.gov/sites/production/files/2015-10/documents/legionella-factsheet.pdf

Your friend may want to think about a quality water heater being used in all houses that because of their construction has an average standby loss of about 1/2 * F per hour .

hot_rod

Here is a study with some useful info. It is a few years old, I imagine some of the countries listed have standards by now.
I believe the ASHRAE standard is based on chemical treatment.

We have a valve, a thermo balancing valve for buildings with multiple DHW record loops. It allows the loop to be elevated above 140F to all the branches. It has a dual function as a balancing valve and anti legionella function.

Public buildings and infrequently used second homes would be wise to implement some type of anti legionella function.

D107

Thanks for the links Hot Rod. Below I have put links to some info I have uncovered. To sum up so far, the idea that one can 'seal' a hot water heater from legionella seems impossible, since, if I am understanding, the disease is not so much airborne in a HWH but comes from oxygen within the water. Makes me wonder about those Legionnaires-filled water towers and if the bacteria in them came from oxygen within the water or outside air. I have seen info that suggests that though the water towers got all the headlines, the greater danger comes from within more standard potable water systems, both in hospitals and residences. It also seems, to reiterate what others have said on this thread and in some of my links below, that chlorine in municipal water is not really set up to kill all the bacteria, but mostly the coliform, which it does pretty well. So, if I keep my HW tank at 140, mix down to 120 at the faucet thereby expanding my hot water tank's capacity at minimal standby losses AND greatly reducing the risk of Legionnaires' disease, seems like a win-win. Even if I sporadically instituted those hot purges at 170º of tank and water pipes, that would only be temporary anyway. If some of the links below don't connect, just Google the title of the article.

Factors Promoting Survival of Bacteria in Chlorinated Water Supplies
http://pubmedcentralcanada.ca/pmcc/articles/PMC202520/pdf/aem00108-0033.pdf

Susceptibility of Legionella pneumophila to Chlorine in Tap Water
http://pubmedcentralcanada.ca/pmcc/articles/PMC239530/pdf/aem00168-0178.pdf

EPA Legionella: Drinking Water Health Advisory, Marcy 2001
https://www.epa.gov/sites/production/files/2015-10/documents/legionella-report.pdf

Disinfection of water distribution systems for Legionella. (Abstract only)
https://www.ncbi.nim.nih.gov/pubmed/9643393 Lin, YS, Department of Civil & Environmental Engineering, University of Pittsburgh, PA, USA. June, 1998

Disinfection of water distribution systems for Legionella: a review of application procedures and methodologies. Muraca PW, EPA Pittsburgh PA February, 1990
https://www.ncbi.nim.nih.gov/pubmed/2179401

Susceptibility of Legionella pneumophila to chlorine in tap water. J M Kuchta, S J States, A M McNamara, R M Wadowsky, and R B Yee Nov 1983
https://www.ncbi.nim.nih.gov/pmc/articles/PMC239530/?page=5

HSE (Health and Safety Exchange) Managing Legionella in hot and cold water systems.
http://www.hse.gov.uk/healthservices/legionella.htm

HSE (Health and Safety Exchange) Legionella and Legionnaires’ Disease
http://www.hse.gov.uk/legionnaires/index.htm

Efficacy of Various Disinfectants against Legionella in water systems
Ford Research Laboratory, Dearborn, MI 48121, USA. bkim@ford.com
https://www.ncbi.nlm.nih.gov/pubmed/12418646

Dangers from Legionella in Domestic Hot and Cold Water Systems http://www.kingdomhousing.org.uk/repairs/wp-content/uploads/sites/10/Reducing-the-Risk-of-Legionella.pdf

Maryland Dept of Health and Mental Hygiene Report of the Maryland Scientific Working Group to Study Legionella in Water Systems in Healthcare Institutions, June 14, 2000
http://phpa.dhmh.maryland.gov/IDEHASharedDocuments/Legionella-Scientific-Working-Group-Guidance.pdf

Legionella 2003 An Update and Statement by the Association of Water Technologies (AWT)
https://www.awt.org/pub/035C2942-03BE-3BFF-08C3-4C686FB7395C

US Dept of Labor, OSHA Section II:C-1. Legionnaires’ Disease Domestic Hot-Water Systems
https://www.osha.gov/dts/osta/otm/legionnaires/hotwater.html

42 Questions on Legionnaires’ Disease, Legionnaires’ Disease Foundation (Stichting Veteranenziekte)
http://www.legionnairesdisease.nl/about-legionnaires’-disease/42-questions-on-legionnaires’-disease#2.1
http://www.stichtingveteranenziekte.nl/wp-content/uploads/2015/11/SV_Folder-How-to-cope...2015.pdf

FAQs
http://legionella.org/faqs/
Legionnaires' disease is a global public health issue. According to CDC's Morbidity and Mortality Weekly Report (August 2011), Legionnaires' disease increased 217% between 2000 and 2009. The disease-causing bacterium, Legionella pneumophila, is a waterborne pathogen found in natural and man-made water systems. Both potable and non-potable (utility) water supplies harbor Legionella pneumophila, and have been linked to outbreaks of both hospital- and community-acquired Legionnaires' disease.

Special Pathogens Laboratory, Legionella in Homes
http://www.specialpathogenslab.com/legionella-in-homes.php

New Perspectives in Monitoring Drinking Water Microbial Quality https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3037048/

hot_rod

And the Ashrae standard 188, probably the standard most apt to find it's way into codes.

Although it sounds like it does not give specific treatment options?

ttp://amienvironmental.com/ansi-ashrae-standard-188-legionellosis-risk-management/

KC_Jones

This may be a touch self serving, but this is something my company participates in to get the word out about the problem.

http://preventlegionnaires.org

I also work closely with the engineer who co-authored ANSI/ASHRAE Standard 188-2015, Legionellosis: Risk Management for Building Water Systems.

Our company is close to this issue as it directly effects us.