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What is windscreen wiper fluid?

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Updated 11 Oct 2019

Rachel White

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It’s a right royal pain when the car in front of you activates their windscreen wipers only for the wiper fluid to overshoot their entire vehicle and land all over your nice clean car . . . grrrrr!

Annoying maybe, but windscreen wiper fluid does have an important job to do, so don’t get too upset with those people who are doing the right thing but don’t know how to adjust their wiper fluid jets.

It’s a driver’s responsibility to make sure the car they are driving has a clear field of vision. That means there must be no obstructions, no dirt, debris or rainwater obscuring the view of the road ahead. Hence the invention of wiper blades.

They are there to remove obstacles from the window and if they’re not working correctly - or you choose not to clean the windscreen - then you could be fined. Even worse, you may cause an accident. After all, you can’t drive safely if you can’t see what’s in front of you.

A wiper blade has a rubber edge that is in constant contact with the windscreen. When it rains, the wiper motion removes water away from the windscreen and the blades need no assistance.

However, the wipers also work to remove debris, bugs and dust that can get kicked up onto the windscreen. To do this effectively, they require the aid of wiper fluid. If they are activated without the use of fluid, dry material on the windscreen can be smeared across the glass restricting visibility even more.

Why should we use windscreen wiper fluid?

Why do we need to use windscreen wiper fluid when water is convenient and free? Well, water alone does not contain the cleaning agents required to help remove gunk effectively from the windscreen.

Water can also go bad when it sits in a tank and the wiper washer hoses for long periods of time. In some cases, water used in wiper washer tanks has been known to harbour harmful bacteria (such as legionella) - a situation that is potentially hazardous if the water is subsequently sprayed.

What is in windscreen wiper fluid?

Wiper fluid can be found in different variations but is typically a combination of detergent and solvents and may contain anti-freeze, ethylene glycol and isopropanol. Some wiper fluids will come diluted while others may be a concentrate. It is recommended to dilute the concentrate with deionised or distilled water to avoid marks on the windscreen. There are some excellent non-toxic, environmentally friendly wiper fluids on the market.

Some people choose to make their own wiper washer fluid, but this is not recommended due to the chances of it foaming or damaging the paintwork and, in some cases, the homemade concoction could be doing more harm than good.
The aim of the windscreen wiper/fluid system is to clear the windscreen effectively. A good wiper fluid will allow the wiper blades to move smoothly across the glass assisting in washing away any road grime, bugs and debris.

It’s good to get into the habit of checking and filling up the wiper washer tank levels regularly - when the car gets washed is usually a great time. The last thing you want is to be fined for having a dirty windscreen.

Don’t forget, wiper blades do wear and will need to be replaced numerous times over the life of the vehicle. Here is an article on wiper blade replacement. And, if you’re not comfortable topping up the wiper washer fluid, have an AutoGuru mechanic do it for you at your next service.

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Written By

Rachel White

Rachel spent her early adult life around cars, motorsport and hands-on with her own cars. This interest moved into various careers within the Automotive industry. Joined with her passion for writing, Rachel loves putting the two together to share her experience, so we can all become AutoGuru’s.