How Might Legionella Get into A Car's Windshield Washer Fluid?

Otto Schwake, PhD, Department of Civil and Environmental Engineering at Virginia Tech, postulates how Legionella might get into automobile windshield washer fluid and if there is any way to prevent it.

Interview Transcript (slightly modified for readability).

“These are ubiquitous organisms; they’re found all over the place. Their main habitats in nature are fresh water, rivers, and lakes, but anywhere from nearing boiling geyser runoff, to permanently below zero Antarctic lakes, [are places] we can find these microbes. So, it shouldn’t be a surprise that they get into our tap water a lot, and that’s really where we think they are getting into washer fluid. [This can happen] by car owners just putting straight water into their cars, or deluding a concentrated washer solution, or the washer manufacturers themselves using nonsterile water — which I don’t know, but I would predict they’re not going to be sterilizing their water too much, but they’re maybe treating it somehow. We think that it’s really the tap water that’s getting contaminated with Legionella, originally from lakes or rivers, wherever the tap water source is, and eventually getting into the cars.

Now, is there a way to prevent it? We don’t know; it’s really hard to say. Preventing it [from] getting in the cars, [such as] boiling your tap water, boiling your washer fluid, kind of defeats the purpose. At this stage in the research where we’re really just learning where they are in cars, it’s kind of premature to say if there’s a way to prevent them from getting in there in the first place. [If] you talk to different people about this project, you [can discuss] ideas about ways to lower the numbers once they’re in there, but again, until we get a better grasp on [where] they’re in cars, we can’t really say how we can stop them from getting in cars.”