Written by The Authority Podcast 6:36 pm Uncategorized

Can Shower Filters Prevent Legionella?

The article below is the transcript from IAPMO’s The Authority Podcast (Season 3, Episode 4) interview with Dr. Janet Stout, executive vice president and founder of Special Pathogens Laboratory, who discusses the threats of Legionella and what steps communities should consider in new home construction and remodeling.

Christoph Lohr: We usually think about the Legionella threat in terms of hospitals and buildings. But did you know the Legionella threat can impact home water systems too? Joining me for the second time, on today’s podcast I’ll be speaking with Dr. Janet Stout, executive vice president and founder of Special Pathogens Laboratory, who will discuss the threats of Legionella and what steps communities should consider in new home construction and remodeling.

Here’s our discussion.

Dr. Stout, welcome to the show. 

Dr. Janet Stout: My pleasure to be with you, Christoph. 

Christoph Lohr: We’re really excited to have you back and I always enjoy our conversations. It’s been a little while, but let’s dive back into it. For our listeners, what is Legionella and how do people become infected?

Dr. Janet Stout: Legionella is the bacteria that causes a life-threatening form of bacterial pneumonia called Legionnaire’s disease.

And it probably surprises people to know that this bacteria is in the water coming out of their faucets and showers. 

Christoph Lohr: How do people become infected from the water that’s coming from their showers and faucets? 

Dr. Janet Stout: Historically, the usual mode of transmission or how people become infected is called aerosolization. It means that the bacteria in the water, it’s into a mist or an aerosol, and we breathe it in, and so it has a direct pathway into our lungs. There’s also another way called aspiration where you’re drinking basically a glass of water that has Legionella in it or ice, and then it transiently colonizes the upper airway and little bits and pieces of those droplets go down into your airway via aspiration. 

Christoph Lohr: Basically when those bacteria make their way on little droplets that get put into the air from spray, that’s where there’s some concern there. 

Dr. Janet Stout: Yes. 

Christoph Lohr: Is Legionella a concern for bathrooms in single-family homes or other types of buildings?

Dr. Janet Stout: That’s a great question and one that we asked very early on in our research. It goes back to the 1980s, not long after the discovery of the disease at the American Legion Convention in Philadelphia in 1976, and we found Legionella. We looked first in large buildings like hospitals, where we knew disease was occurring.

And then we asked the question that you just asked; Would we see as much in single-family dwellings? And about 50% of large buildings have Legionella. And our study and others showed only about 10% of single-family residential buildings, homes, had Legionella, simpler water systems. And then actually we did a subsequent study funded by the EPA – Environmental Protection Agency – asking us to go backwards from somebody who had Legionnaire’s disease and ask the question: Did they get it from their home? And we actually found about 20% of the cases acquired it from their homes. But the good news about this study was that the people that got Legionnaire’s disease from their homes were highly compromised, or in that high-risk group being elderly, having immunosuppressive conditions like leukemia, or one woman I remember was post-breast cancer chemotherapy. 

Christoph Lohr: It sounds like from what you’re describing then, it’s homes that are more complex or, or buildings I should say, that are more complex. Single-family homes tend to be pretty simple from a plumbing standpoint, but maybe a multifamily-home apartment – it’s a little bit more complex – could have a little bit of an increase in risk.

And then the population that’s in these dwellings, if you’re somebody that has already been sick, then you have a little bit of an increase in risk.

Dr. Janet Stout: Yes, and the traditional risk factors for Legionnaire’s disease are being older – it might surprise your listeners that older means older than 50 – chronic lung disease, smokers, immunosuppressive conditions, and certainly the most at risk would be a transplant recipient. 

Christoph Lohr: All right, so we kind of set the stage here of sort of that transmission path, the concerns of the water droplets getting put into the air through spray, and then the types of people and the types of buildings that are concerned.

Let’s kind of dive into the details here in terms of like the showers and faucets. What is the shower filter that protects against, or faucet filter, that protects against waterborne pathogens and how do they differ from some tap filters? 

Dr. Janet Stout: Bacteria are very small, as you know, and so the size of Legionella is in microns, and so the pore size of filters has to be 0.2 micron or smaller in order to exclude bacteria, including Legionella.

We first had experience with these what are called point-of-use filters, where you put it on the fixture at the end of the faucet or the end of the showerhead, had our first experiences with those in health care institutions, and we’ve done many, many studies ourselves demonstrating efficacy of them.

When people are immunocompromised at home, for example, what I say is, what would I want to do? And I say, well, I would want one of these point-of-use filters on the shower that I use, and on the most-used faucet that I would use to protect me from not only Legionella, but some other bacteria that could cause infections in immunosuppressed people.

Christoph Lohr: Fascinating. There are some general recommendations out there for these filters being able to do that. How does someone know if a given filter will really prevent Legionella in the shower? Are these filters regulated in any kind of way? 

Dr. Janet Stout: Yes. They have to sort of pass a test, and I know that people that may be listening don’t have access to peer-reviewed scientific journals, but if they do, for example, our last publication was in the American Journal of Infection Control in 2019, where we not only evaluated one of the new point-of-use filters on the market by one of the manufacturers, but we also did an overview of all of the manufacturers that had point-of-use filters on the market at the time. If you don’t have access to that, how do you know that these filters are working? There are different organizations, American Society of Testing Materials (ASTM), National Science Foundation (NSF), also ASSE has a standard now.

You’re looking to see was that filter challenged by following these standards with a known concentration of bacteria, and are they successful at holding those bacteria back so that none came out the other end of the filter? You have to read the fine print just like on any product. 

Christoph Lohr: I think you kind of talked about it, but maybe explain a little bit further how these Legionella filters are tested to know that they perform. Are there any particular standards or any test protocols that you’re aware of that kind of test toward that?

Dr. Janet Stout: Well, historically the standard has used a surrogate organism. It’s another bacteria called pseudomonas and a certain very high concentration, say a million per milliliter, is passed through the filter. The ASSE standard, the LEC, is the only one that I know of. It’s Legionella reduction in treatment devices is the only one I know that specifically addresses Legionella, and you can tell the audience what ASSE stands for, Christoph.

Christoph Lohr: It is ASSE International, but yes, that’s very true, Dr. Stout. These standards, it does seem that these standards really have an impact in terms of the industry, let’s say, in terms of giving some confidence in knowing that these can perform. 

Dr. Janet Stout: Yes, and FDA also makes recommendations for following certain standards for validation of product claims. It is really important for the consumer, and for them to have faith in the performance of these filters, to have these standards in place. 

Christoph Lohr: Definitely, definitely. A lot of this sounds pretty high tech, right? We’re talking about microbiology and certificates of confidence in essence.

But then I’m sure our listeners are probably going to ask, can anyone sell these filters or do you need like a professional installer that has a lot of training. Do installers need some kind of specialized training? What’s your experience been with that? 

Dr. Janet Stout: My experience with this, regardless of the manufacturer, is they are interested in making sure that the installation is not so onerous that you an average person couldn’t do it. Most of these, there’s an adapter piece that goes on the end of the threaded end of a faucet or the end of the shower wand or hose, and that adapter piece then sometimes there’s a quick connector they just pop on. Then after a certain period of time, you have to replace them.

You don’t have to be a plumber to install these devices. I think that’ll give a lot of our listeners some peace of mind. But you kind of mentioned something there in passing, which was talking about replacing them. What’s your awareness been in terms of ongoing maintenance and knowing that you’re still protected with these filters?

Dr. Janet Stout: Depending on the manufacturer, and this was something that we put in the supplemental material of our article, their length of life. How long before you have to replace them differs tremendously from manufacturer, and even some manufacturers within their product offerings have different time points – 30 days, 90 days, 120 days.

The tricky part is those claims of use really depend on the water quality. As we talked about, the pore, the hole that the bacteria are stopped is very, very small micron, 0.2 micron. There’s a lot of dirt that’s much bigger than that that’s in our water. It might surprise people to know that, but it clogs the filter.

In some parts of the United States or the world, the water is cleaner in terms of those particulates than other places, and so if it has a lot of particulates, it’s going to clog that filter and you’re going to have to replace it more often than what the manufacturer suggests is sort of average use. Sometimes people are surprised when the filters don’t last as long as what they expect.

Christoph Lohr: That makes sense. Well, obviously filter replacement and purchasing filters, there’s probably always the concern of affordability and access to this. Any thoughts on what can be done to help people in underserved areas with poor water quality who might not be able to afford a Legionella filtration system?

Dr. Janet Stout: I think in an underserved area, a point-of-use filter probably isn’t the solution for them. It’s probably disinfectant in the water or boiling the water. As primitive as that sounds, it’s very, very effective at controlling exposure to any number of pathogens, including Legionella, so that’s probably a more practical approach.

The price point historically has not been cheap, so maybe as more and more manufacturers get into the offering and it’s greater and greater acceptance, uh, the price may go down. But I think in a poor economy, probably water safety takes sort of a more basic approach like boiling water.

Christoph Lohr: That makes sense. We’ve talked a lot about Legionella, but is there any other health or wellness benefits to Legionella filters? Obviously people, tthey search for filters that benefit their skin and hair. Are there any other sort of unintended benefits instead of consequences when it comes to using a Legionella filter for your shower faucet?

Dr. Janet Stout: To me, when you ask that question, Christoph, the thing that comes to my mind is, it’s not just Legionella in our water that causes infections, particularly for people who are compromised. There are other bacteria like pseudomonas, like nontuberculous mycobacteria. For example, nontuberculous mycobacteria is problematic for patients with cystic fibrosis. Similar with pseudomonas aeruginosa.

These bacterial exclusion filters, that 0.2 micron or lower pore size, will exclude those pathogens as well. Again, I always think, if I’m immunocompromised, what would Janet Stout, the microbiologist-now-Legionellologist, what would I want to do? What would make me feel safe during that period of compromise? And a point-of-use filter would do that, and it would protect me from any number of potential pathogens. 

Christoph Lohr: Last question, because we’ve had you on the podcast before, Dr. Stout, and thank you again for your time today; we’d love to have you on again. What do you think, if it’s in about a year’s time, we have you coming back on the podcast to talk about something Legionella obviously related. What do you think we’re going to be talking about in terms of Legionella? 

Dr. Janet Stout: Well, what I would love to be able to say is that with new water management requirements from ASHRAE – an engineering organization – and in health care the Centers for Medicare and Medicaid Services and the Joint Commission, that we would be talking about how the number of cases has been dramatically reduced compared to historical values. I would love for that to be what we’re talking about. I’ve lived long enough to say, I’m not going to be cynical, but I’m going to be pragmatic. We may still not be where we need to go in a year’s time, but this is the direction that we want people to go in, and I’m really grateful for your podcast to raise awareness of the availability of some of these things like point-of-use filters to prevent cases of community-acquired or even hospital-acquired Legionnaire’s disease.

Hopefully we’ll be talking about that.

Christoph Lohr: I love the aspirational tones of that. 

Dr. Janet Stout: That’s right. 

Christoph Lohr: Hopefully that aspirational tone sets the mode. 

Dr. Janet Stout: Well, our mission is a BHAG – big, hairy, audacious goal – and that is to end Legionnaire’s disease. I say it’s not so much an audacious goal as an achievable goal with help from people like you.

Christoph Lohr: That’s too kind of you to say, but thank you, thank you. Well, Dr. Stout, on behalf of The Authority Podcast and IAPMO, just thank you so much for taking time out of your busy schedule to record this with me, and looking forward to having you on again in the near future. 

Dr. Janet Stout: Yeah, I would love that, and thank you so much for the opportunity today.

The Authority Podcast

The Authority Podcast: Plumbing and Mechanical is a podcast from the International Association of Plumbing and Mechanical Officials (IAPMO).

When talking about the built environment, we would do well to remember, "We shape our buildings, and afterwards, our buildings shape us." Therefore, on each episode, we'll discuss the latest trends from IAPMO in plumbing and mechanical safety, sustainability, and resiliency with some of the brightest minds in the industry. Join your host, Christoph Lohr, and together we'll explore the ways we can make our buildings shape us for the better.


Last modified: January 29, 2024