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The Mumsnet guide to Kärcher Window Vacs

For clean, smear-free windows at the touch of a button, the Kärcher Window Vac is Mumsnetters' go-to product. But what makes it so great? Read on for everything you need to know.

By Mumsnet HQ | Last updated Dec 5, 2023

Karcher window vacs

“I may have to set up a window cleaning business to satisfy my new lust.”

“If my house was burning down there would be two things I'd save: my son and my window vac.”

As proven time and time again, Mumsnet users love a Kärcher Window Vac. Whether they're using it for cleaning windows, sucking up spills or clearing condensation, they say it's a handy piece of kit to keep around the house. Although it really had its heyday a few years back, there were still 47 Mumsnet posts mentioning the window vac last year, and 179 mentioning Kärcher – proving there are still a fair few questions to be asked.

Whether you're considering buying one or already own one and have some questions, read on for some tips and tricks on how to get the best out of your Kärcher Window Vac.

Woman using a Karcher window vac

What is a Kärcher Window Vac?

Kärcher's Window Vac pretty much does what it says on the tin – it vacuums up excess moisture. Among other things, this makes it really handy for helping when you decide to clean windows, shower panels, mirrors, or any other flat surface in your home.

Although the vac doesn't do the cleaning for you (and therefore does still require a bit of elbow grease), it definitely makes cleaning much easier – sucking away the excess water so it doesn't pool on the surface below. It also means you won't have to wring out or dry anything.

Plus, it can be used to clean up the inevitable drinks spills and bathroom tidal waves which come hand-in-hand with a house full of smaller people.

“Mine does the windows in minutes, and it's great for condensation in the winter. I also use it on my shower screens everyday, and for mirrors. It's one of the best gadgets I have.”

“We purchased ours to get rid of the condensation on the bottom of windows in winter, but also because my daughter literally swamps the bathroom with moisture/steam. We use it to suck water off the tiles, walls, and sometimes ceiling. Would not be without it for that – have killed two already but it gets a lot of work done. It even helps to prevent mould.”

“I love using it on shower screens, bathroom tiles, the bathroom mirror, the fish aquarium – but mostly on my car windscreen! Great also for clearing condensation from car windows on misty mornings.”

How do you use a Kärcher Window Vac?

All it takes is giving the surface a good soaking with water and your cleaning product of choice (Kärcher do produce their own cleaning solution, but Mumsnetters swear washing up liquid does a pretty good job, too), a scrub with a microfibre cloth or similar, then a swoosh around with the window vac to collect up all the water. And, hey presto, you'll have shiny, clean (and hopefully smear-free) windows.

You can achieve clean windows, mirrors, shower glass and even floors in four simple steps:

  1. Spray your chosen cleaning solution all over the surface

  2. Wipe the surface thoroughly with your cleaning cloth

  3. Use your window vac to remove all the suds and water left behind

  4. Once full, you can simply empty the water straight down the sink

Here's a handy video guide from Kärcher:

Kärcher Window Vac accessories:

There's also a whole host of added extras and replacement parts ready to purchase. Some of them only work with certain models, so make sure to check this before you buy.

Replacement parts:

Extra accessories:

“If you have tiny window panes you need to look at the blade size. The one that comes with it as standard is quite long. I bought the additional shorter one (15cm ish) for doing my small window panes. The blade needs to be able to sit flat against the window like a squeegee would.”

“I bought the basic model which only has the small-size rubber blade, but there's another one which has a large rubber blade plus the smaller one as an attachment.”

What do Mumsnetters like about Kärcher Window Vacs?

With grand testimonies including the one from the Mumsnetter who wanted to set up a window cleaning business just so she could use her window vac more often, what is it specifically that our users like so much about this bit of household tech?

“I have one and I use it daily in the bathroom. I love it! I can get away with scrubbing the bath and shower door about once every three weeks now, instead of them constantly looking cloudy after every shower.”

“I love mine. I have an old house with lots of windows and lots of condensation. With this, I can whip around the whole house in about 10 minutes in the morning, and the job's done. Fabulous bit of kit.”

“Very quick to use and very very satisfying: just slosh the windows clean with whatever you have and then hoover it polished in seconds. All flat surfaces in our house are now squeaky clean for probably the first time ever.”

“Get one, it's the best gadget I've ever bought. Even my teenage daughters want to use it – they argue over it!”

“I bought one recently and have become evangelical about their total fabulousness. So easy to use, so quick, and makes the windows clean up a dream.”

What do people also ask about Kärcher Window Vacs?

How do I stop smeary streaks from being left on my window?

One of the things Mumsnetters like most about their window vacs is the fact that they leave surfaces smear- and streak-free. Occasionally, however, you can still be left with some smudges even after using the window vac. If you're getting less-than-perfect results, try wiping down the blade more regularly.

“Oh and a hint: after each run down the glass, I wipe the blade quickly with a cloth. Seems to help stop the streaks!”

How often does the Kärcher Window Vac need emptying?

One of the main pros of a Kärcher Window Vac is that you can just empty the water straight down the sink when you're finished, rather than having to wring out a cloth over and over. The capacity of all Kärcher Window Vacs is between 100ml-150ml, and the amount of time this will take to fill will depend on how much liquid you use on each surface. If you're mopping up spills, it's more likely to fill up more quickly.

“Mine works really well. I like being able to tip the water away down the sink rather than having to dry a cloth.”

What cleaner or detergent should you use with a Kärcher Window Vac?

Although Kärcher do have their own cleaning solution, Mumsnetters also recommend that you could also use any of the following:

  • Washing up liquid

  • White vinegar (diluted)

  • Dedicated glass cleaner (such as Flash or Windolene)

“I buy the detergent from Kärcher. It dilutes down, think 1:10. It's quite economical, and is the best window cleaning stuff I've ever used.”

“I wash with warm water, a little washing up liquid, and a glug of white vinegar, then finish off with the vac.”

“I use a basin of warm water with a bit of washing up liquid to wash the windows, and then just vacuum away the water. You need a dry cloth just to wipe the bottom of the window where a little water might remain.”

What's the difference between the different Kärcher Window Vacs?

The specifications of your Kärcher Window Vac will vary greatly depending on which model you choose. All models have their standard suction nozzle, a tank for the dirty water, and an LED battery display, but as the models get more advanced you get more features – like re-chargeable batteries and varying nozzle widths.

1. Kärcher Window Vac WV1

Karcher Window Vac WV1

Being the most basic model, the VW1 still does the job nicely, but without some of the bells and whistles the other models boast. Thanks to its cheaper price point, it's your best bet if you're a window vac novice, but be warned: only having the one blade size can be quite limiting. In the box, you get the window vac itself and the charger as standard.


  • Vacuum nozzle width: 250mm

  • Capacity: 100ml

  • Battery run time: 25 minutes

  • Battery charge time: 100 minutes

2. Kärcher Window Vac WV2 Plus

Karcher Window Vac WV2 Plus

The best thing about this model is that it comes with the Kärcher spray bottle, complete with a microfibre cloth. Fill this with whatever solution you want (or the handy sachet of Karcher cleaning fluid also provided), and spritz it all over your window before vac-ing it all off. It's also slightly more premium than the first model thanks to it's quieter technology and longer-lasting charge. In the box, you'll also get your charger, spray bottle, and cleaning solution sachet as standard.


  • Vacuum nozzle width: 280mm

  • Capacity: 100ml

  • Battery run time: 35 minutes

  • Battery charge time: 185 minutes

  • Averages at 35 windows per charge

3. Kärcher Window Vac WV5 Premium

Karcher Window Vac WV5 Premium

Instead of recharging the unit, the WV5 model comes with a detachable, rechargeable battery, giving you the option to buy more than one and get longer uninterrupted use. And even more importantly, the model comes with two different nozzle sizes: the standard 280mm plus a smaller 170mm, perfect for the smaller panes of glass and mirror. There's also a three-stage LED battery indicator, meaning you've got plenty of warning before you run out of battery. It comes with a standard suction blade, narrow suction blade, spray bottle, cleaning solution sachet, lithium-ion battery, and charger.


  • Vacuum nozzle width: 280mm and 170mm

  • Capacity: 100ml

  • Battery run time: 35 minutes

  • Battery charge time: 185 minutes

  • Averages at 35 windows per charge

4. Kärcher Window Vac WV6 Premium

Karcher Window Vac WV6 Premium

By far the sleekest-looking model, the WV6 Premium is the cream of the crop. With a display showing the number of minutes of charge left, silicone lip technology, and a larger dirty water tank, it's definitely the easiest to use and the best bet if you're going to use it a lot. It comes with a whole host of extra accessories, too – including a quick charger, outdoor microfibre wiping cloth, dirt scraper and interchangeable nozzles, as well as the spray bottle and sachet of cleaning fluid.

It's important to note that, unlike the WV5 Premium, the battery on this model is not detachable.


  • Vacuum nozzle width: 280mm and 170mm

  • Capacity: 150ml

  • Battery run time: 100 minutes

  • Battery charge time: 170 minutes

  • Up to 215 windows per charge