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Do I Have to Use Windshield Wiper Fluid or Is Water OK?

CARS.COM — If you have ever run out of windshield washer fluid when you didn’t have any more on hand, you may have wondered whether you really need special fluid or if you could just use plain water instead. Water is readily available almost anywhere, and topping off your reservoir with it would save you from needing to make a trip to the store. Is plain water an acceptable substitute for windshield washer fluid, though?

Related: More Maintenance Coverage

Windshield Washer Fluid Versus Plain Water

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 specialized cleaning fluid for removing bugs, bird droppings, road grime and other crud that collects on windshields. Windshield washer fluid contains ingredients that are meant to clean up those stubborn messes. Most products are made of methanol and other alcohols like ethylene glycol. Many also contain small amounts of ethanol or antifreeze made from methylated spirits to keep the product from freezing during the winter months. The ingredients in washer fluid work together to give you a clean, streak-free windshield no matter how cold it is outside.

The main benefits of water are that it’s cheaper than windshield washer fluid and more 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 during cold weather. 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 because you didn’t want to stop at the store to pick some washer fluid.

Windshield Washer Fluid Works Better But Comes at a Price

Fluids formulated specifically for cleaning windshields 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. Some people, however, use ingredients like white vinegar and distilled water to clean windshields without the use of toxic fluids.

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.

For more on your vehicle’s various fluids, check out the video below.

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