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How to Use a Karcher Window Vacuum for Best Results

Written by James Hall |

how to use a karcher window cleaner

Not sure how to get the best window cleaning results from your Karcher window vac? Here’s our complete guide for how to clean windows with a Karcher window cleaner.

Manual window cleaning is hard work that often provides disappointing results – especially if there are streaks at the end! Cleaning all the windows in your home can also be a time-consuming process.

A Karcher window vacuum can make cleaning your windows much faster and more efficient. It’s still important to know how to properly use the device, however, otherwise you might not get the results you hoped. In this article, we’ll go through a simple method for using your Karcher to clean windows.

Note: This article focuses on the Karcher WV6, but the tips should apply to all versions of Karcher’s window vacuums.

How to Clean a Window With a Karcher Window Vacuum

Example of a Karcher window vacuum

Step 1: Fill the Spray Bottle

The first step is to fill up the spray bottle. Karcher provides detergent for window cleaning (the “Karcher glass cleaning concentrate”), so mix this with water inside the bottle.

We also recommend wetting the soft cleaning pad on the bottle. This helps to prevent the pad from absorbing too much of the cleaning solution while you’re wiping.

Step 2: Apply Detergent to the Window and Wipe

Once you’ve mixed the detergent with water and wetted the pad, you can use the spray bottle to apply the solution to the window.

Be generous with the detergent solution! The goal is to moisten the entire window surface and loosen dirt, so you need plenty of solution. It’s also important that there’s enough fluid on the windows that it doesn’t dry before you suck it up, as this can cause streaks.

Use the soft cleaning pad of the bottle to wipe the window as you’re applying the solution. This spreads the detergent across the window and removes dirt.

Tip: The windows should be relatively wet after this step. Applying too little solution to the glass is a common mistake that means your windows are more likely to have streaks.

Step 3: Use the Karcher Window Vacuum to Remove the Water

The great thing about using a window vac is that all the dirty water is sucked up into the vacuum cleaner. This makes it much less likely that the solution splashes on carpets or furniture, which is a big problem when cleaning indoor windows.

Now that the window has been cleaned with detergent, the next step is to use the Karcher Window Vacuum to suck up all the dirty water. Make sure you do this quickly after applying the solution, as it’s the act of removing dirty water before it dries that prevents streaks from forming.

You don’t need to press too hard for this step. The key is to use even pressure to remove as much water as possible.

You may find that where you started vacuuming from won’t be quite as clear as the rest of the window. If this is the case, use a small and clean microfibre cloth to wipe away these sections.

If you’ve completed these steps correctly, the window should now be clean and streak free. You can use the same process on conservatories, mirrors, glass tables, tiles, and other glass surfaces around the home for a streak-free finish.

Tip: Are you cleaning a high window? Karcher produces an extension pole kit for their window vacuum that can greatly increase the reach.

Frequently Asked Questions

Why Does a Karcher Window Vacuum Sometimes Leave Streaks?

If used correctly, a Karcher window vacuum should leave a streak-free finish. If you’re noticing streaks on your windows after cleaning, then the issue is likely to be with the vacuum’s squeegee. Here are some of the most common causes of streaks:

  • Squeegee blades can become worn over time. Uneven patches of fabric start to develop, which leads to streaks on the window. The simplest solution is to turn over the squeegee to get a fresh side, although you may need to buy a new squeegee once both sides are worn.
  • Dirt on the vacuum’s squeegee can also leave streaks. Use the spray bottle’s cleaning pad to wipe the blade before using it to clean the window.
  • Avoid cleaning windows when there is direct sunlight or in hot weather. If the cleaning water dries too quickly then it’ll leave streaks. Ideally, you should clean windows on a cloudy day.

Another common problem is not using enough cleaning solution. Too little solution will allow the window to dry before you vacuum up the dirty water, which will cause streaks. For hot days, you may need to use more solution – especially on exterior windows.

How Often Should You Clean Windows?

The simple answer is that you should clean your windows as often as necessary. This will vary depending on your personal preferences, the recent weather, and where you live.

Dust, pollen, and bad weather can cause windows to look dirty quite quickly, so if you want spotless windows you might want to clean them as soon as you notice dirt.

For most people, cleaning windows once every 1-2 months should be plenty though. Many people also use the Karcher window vacuum to clean their windows between professional cleans, as this can save money in the long run by meaning you don’t need to pay a pro so frequently.

Do You Put Water and Detergent in a Karcher Window Cleaner?

You don’t put water inside the window cleaner itself. Instead, you use the provided spray bottle to mix and apply the detergent solution.

The window vacuum is just like a regular vacuum – it sucks up dirty material rather than applying it.


A Karcher window vacuum can make cleaning your windows much faster, easier, and less messy.

After applying the Karcher detergent using the provided spray bottle, wipe the windows with the bottle’s cleaning pad before sucking up the dirty water with the vacuum. As long as the squeegee isn’t worn, you should end up with a streak-free and clean window.

Do you have any question about how to use a Karcher window cleaner? Please let us know in the comments section below. You may also want to read our guide to window vacuums.

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