• Jun 15, 2010
If you use standard tap water in your windshield washer fluid reservoir instead of a cleaner, you may have effectively turned your vehicle into a biological weapon. Sure, that sounds cool and all, but according to BBC News, the only person you're going to be hurting is yourself. As it turns out, using plain water can cause the washer fluid system to become a breeding ground for Legionella bacterium – the same nastiness that causes Legionaires' Disease and pneumonia. Spray your windshield and the bacteria becomes airborne, allowing it to easily enter your lungs and wreak havoc with your immune system.

Researchers discovered the hive of scum and villainy lurking under the hood by attempting to discern why professional drivers were five times more likely to become ill than their amateur counterparts. After a little scientific sleuthing, the lab coats unearthed the bacteria. So do the world a favor and top off your windshield washer fluid reservoir with some sort of purpose-built cleaner. The stuff will kill the infection-causing bacteria and will keep the fluid from freezing in the winter. Not bad for 99 cents a gallon. Thanks for the tip, Kris!

[Source: BBC News | Image: williac – C.C. License 2.0]


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  • 26 Comments
      • 4 Years Ago
      I buy a case on sale when I'm running low and can usually get them for $1/gal that way. It is also what most everyone uses in their meth injection systems for turbo and supercharged engines.
      • 4 Years Ago
      Its not even $5 ... At wall-mart its like $2 ! Cheap @#$%!
      • 4 Years Ago
      Reminds me of when we used to turn the passenger side nozzle so we could squirt our friends as they tried to get in the car.
      • 4 Years Ago
      so do people make it a habit of spraying their windshield with their windows open and doing 70 down the highway?

      The fact that I've seen places trying to sell the stuff for more than what it costs to buy a gallon of gas means a big "no thanks" from me.

      Hooray for being in Texas where it never freezes
        • 4 Years Ago
        Car ventilation systems often draw air in from under the back-side of the hood. So if you are driving with the your windows up and the A/C blasting, windshield washer sprays right over the intake of your A/C, blowing it all in your face.
      • 4 Years Ago
      I only ever use the Rain-X stuff (orange color). Since it's Rain-X, it makes raindrops bead up and roll off.
      • 4 Years Ago
      It's not always easy to get screenwash in the UK.

      I went to an Esso gas station in London the other day, not a small one, has its own car wash block, to get a bottle of summer screenwash. They had about 15 bottles of the winter variety (good to -30)...

      Texaco was "out of stock", so I ended up on a supermarket gas station, where they had about 30 bottles, incredibly dirty and dusty...

      Few years ago, in Wales, I went through about 4 stations to get a small bottle of concentrate.... so I had to purchase destilled water too and mixed it up.

      A developed motoring nation? Don't think so.
      • 4 Years Ago
      Mos Eisley
      • 4 Years Ago
      If you don't want to spend the $1.50 on fluid, a mixture of distilled water and windex works pretty well too.
      • 4 Years Ago
      Home made Audi OEM style windshield washer fluid:

      30 parts 70% Isopropanol Alcohol
      7 parts Methanol (poison - careful)
      6 parts water

      Alternative recipe:

      The yellow Audi stuff is 49% isopropyl alcohol, 16% methanol, and 35% water.

      Apparently less harmful to the paint and trims. Less likely to foam or collect as icy slush in extreme conditions.

      http://forums.audiworld.com/showthread.php?t=97765

      Ammonia would be like peeing on your car, right? Can't imagine that's good for the paint. They use the stuff for getting rid of wax buildup on floors....
        • 4 Years Ago
        Chemicals do different things at different concentrations. And saying ammonia is bad because urine contains a tiny amount of it is just silly. Urine contains a LOT of water, so is it bad for my paint if I put water on it?

        My understanding is ammonia will strip wax over time. My current car doesn't have headlight washers (what gives, Cadillac?) and I don't wax it anyway! If you're concerned about your wax, then definitely use alcohol instead.
        • 4 Years Ago
        Spincycle: I'm not sure I would want to repeatedly spray the paint on my car with even a weak ammonia solution, only to have the gunky residue being cleaned away, sit there for several days between washings. I know ammonia evaporates pretty fast, but wouldn't it take longer once it is absorbed by the debris? Ammonia based window cleaner is sometimes recommended as part of the paint prep for removing grease and wax when painting your car.

        I spend a lot of elbow grease keeping it nice and shiny! :)

      • 4 Years Ago
      How cheap can you be? It only costs $5 for a gallon of this stuff
        • 4 Years Ago
        "Why not just put 2 cups of ammonia in the reservoir and fill the rest of it with water?"

        Why bother being a chemist when in most parts of Britain, temperatures rarely drop much below freezing point and you can get away with good old tap water? Legionnaire's disease is serious, but this story is going to be simple scaremongering for most people.
        • 4 Years Ago
        "I agree even 5x the risk isn't much risk. But ammonia is very cheap and you aren't being much of a chemist when you put a little in.

        If you've cleaned a window before you know how much more effective ammonia is at cleaning windows than just tap water. Don't you want your windshield to be the cleanest window you own?"

        Quite typically, the average Autoblog poster goes overboard. I'm not speaking of from a car enthusiast's point of view, I'm speaking from Joe Public's. Most people won't give a toss and just use tap water. They're not going to go out of their way and think "hmm, one part ethanol, one part ammonia, one part H20, etc". I've used tap water before and it's been fine - in the Severn Trent region you can get away with it generally. I use distilled water and I also use Rain-X's brand too occasionally. All work fine for me.
        • 4 Years Ago
        $5 or $0.89....windshield washer fluid is just as important as oil and brakes. If you can't see clearly, an accident is most-likely in your future.

        Whether you're a doctor, a cashier, or a college student...it should be easy to recognize why tap water in the reservoir is a bit silly.
        • 4 Years Ago
        college student


        game set match
        • 4 Years Ago
        Why not just put 2 cups of ammonia in the reservoir and fill the rest of it with water? Ammonia is the main ingredient in Windex anyhow and will prevent any bacteria from growing-- and won't harm paint.
        • 4 Years Ago
        "How cheap can you be? It only costs $5 for a gallon of this stuff"

        It isn't a case of being cheap. In the UK, windscreen washer fluid contains ethanol which can be harmful to a car's paintwork. So many people don't use it.

      • 4 Years Ago
      I never even have the need to use washer fluid. I don't know what people drive through to have to use washer fluid.
      • 4 Years Ago
      Damn... I did that ish a bunch when I was younger. WTF knew.
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