Why switching to non-toxic windshield wiper fluid is a good idea
Cars are notorious for having mysterious problems that only the owners can perceive, not mechanics. As soon as you bring the car to the dealership or mechanic, like a dog on the way to the vet, all is fine. No problem whatsoever, no replicable problem at all. Arghh! We’re having an air quality problem with our family car, and while researching online, it seems I’m not the only one. I wanted to avoid going to the dealership with it, because several others noted that OF COURSE the problem will not reappear when the mechanic drives and tests it…
It turns out that cars of different brands are having the same problem (BMW, Tesla, Subaru, Ford for example). The air coming from the vents intermittently smells like chemicals. It’s not musty like mold (if it is a musty smell, see our article on fixing that). From various posts on owners forums, it could be a refrigerant leak, however in our case, the AC has not stopped running cold. Since I knew that activated carbon takes away chemical smells and it’s also good for removing NOx fumes from other cars on the road, I installed a new cabin air filter with activated carbon. But, 6 months later, the carbon must be used up/deactivated, because here we are again: chemical smell coming from the AC. There are some commonalities: the smell frequently happens during/after driving in the rain, and when the system is not in “recirculation” mode. Finally, an owner and dealer were able to figure it out: windshield wiper fluid. Here is the gist in the owner’s words:
“Here's the gig: the BMW washer fluid has an odor. When you wash your windshield the fluid drains across the cabin ventilation intake under the top of the hood. When you have the AC set to anything other than recirculate, the cabin air samples any vapors that reside in the ventilation intake. The intake has a drain so that rainwater, etc., flows on through, but as washer fluid in the ventilation intake dries it is by definition turning to vapor. We simply took a hose and washed down the windshield, which in turn flushed out the ventilation intake. Back in the car, there was no odor. When we switched on the windshield washers - voila, odor.”
Windshield wiper fluid is like generic residential glass cleaner…it has volatile solvents like alcohol and ammonia to help it dry quickly and leave less streaks. Those volatile chemicals are VOCs, which we are not meant to breathe. It’s a major design flaw, for sure, to have windshield washer fluid draining near the ventilation fresh air intake. Since it’s happening across brands and even in luxury cars, obviously the designers haven’t had it happen in their cars. This post was from 2014, it’s 2025 now, and our 2021 car is quite smelly sometimes. I can’t hold my breath for very long while driving (I’ve tried).
So what did he do? “The fix was extremely simple of course. Run the washers until they are dry. Refill with a different washer fluid. Run them dry again. Repeat. Flush the ventilation intake with a garden hose. Refill the washers with your fluid of choice. All done. Wife happy. Hope this helps others.”
Yes!! I’m pretty sure many of our chemically sensitive readers are elated when they can find a cause and actionable solution. But what “fluid of choice” is non-toxic, since, absent of a good filter, we’re going to be breathing it? Some owners said they only use distilled water in their wiper reservoirs. Upon research, I found that this is not a good idea because it lacks lubrication. Real windshield wiper fluid has lubrication for longevity of the pump, as well as help the wipers glide across the glass.
Enviro-One has a Multi-Use Green Cleaner that can be diluted to use as windshield washer fluid. Enviro-One’s formula has proudly achieved the esteemed “Champion” status, the highest award bestowed by the Environmental Protection Agency (EPA) under their Safer Detergents Stewardship Initiative, Design for the Environment Program (DfE). This award recognizes industry leaders who voluntarily embrace the use of safer surfactants, which are designed to swiftly break down into environmentally benign substances, playing a crucial role in the protection of aquatic ecosystems in both fresh and salt water. Their products have a long list of uses in the home, shop, garden, etc. Although this product is safe, you may have to mix in some alcohol if you live in a cold area, to keep the system from freezing in the winter.
There are a lot of “make your own” recipes that call for alcohol or ammonia to help it dry faster, and to avoid freezing. One poster did this, put it in 3 cars for he and his daughters, and ended up replacing washing fluid pumps and valves because the homemade solution fouled them. So, cheaper and homemade is not always better, especially if you have a luxury car that costs premium dollars for parts and repair. When in doubt, you can always use the manufacturer’s recommended fluid, but replace the cabin air filter every few months with a filter with activated carbon to adsorb the VOCs coming from the windshield fluid.
Photo by Thibault Valjevac on Unsplash
