Wiper Fluid or Is Water OK
If you live in a place where the temperature never gets down to freezing, you might be able to get by with plain water — but even then, water doesn’t have the cleaning power of wiper fluid for removing bugs, bird droppings, road grime and other crud that collects on windshields.
The main benefits of water are that it’s cheaper than wiper fluid and compatible with the environment. Its main drawbacks are its lack of cleaning solvents and detergents, and that it freezes at 32 degrees Fahrenheit, rendering the windshield-washing system on your vehicle useless. So even if you live in a very warm climate, keep in mind those trips to Grandma’s in Minneapolis; you don’t want to get stuck in a snowstorm without the ability to clean your windshield.
Wiper fluids generally do a better job of cleaning than just water and usually won’t freeze until 20 degrees below zero or colder. The bad news about wiper fluid is that it’s typically made of ethanol or methanol, which are poisonous for people and animals and can be damaging to the environment. Wiper fluid also usually includes a dose of ethylene glycol, a toxic alcohol used in automotive antifreeze. Those substances can damage paint finishes as well as some plastic and rubber parts on vehicles.
Because of health and environmental concerns, some vehicle owners resort to making their own wiper fluid from non-toxic substances. We have no experience with these homemade brews and can’t vouch for their effectiveness.
Despite the toxicity of over-the-counter wiper fluids, it can be downright dangerous to drive without them in many parts of the country, especially during the winter. Snow, slush, ice and road salt can quickly make a windshield impossible to see through, and frequent washing with high-potency wiper fluid designed for winter conditions is the only way to clear away the muck so you can see where you’re going.