Kärcher K7 Premium Smart Control Pressure Washer review: the guided way to clean your patio, care and more

The Kärcher K7 Premium Smart Control is Kärcher’s most powerful pressure washer, versatile enough to tackle a multitude of stubborn cleaning tasks around your home and garden. Featuring a high-pressure hose with integrated reel, LCD display trigger gun, telescopic handle, on-board storage system and ‘plug ‘n’ clean detergent system, it also comes with a 3-in-1 Multi Jet lance, T 7 T-Racer Surface Cleaner and a bottle of Stone & Façade detergent.  

With spring in the air and guests being allowed back in our gardens soon, the stonework around our house really needed some attention. The driveway bricks looked dull and dusty, and the garden patio was covered with a variety of unwanted dirt – from moss and mud to faded poster paint dinosaur footprints (an attempt at keeping my son entertained whilst confined to the house). With some new patio furniture also about to arrive, we needed to get the jobs done quickly, so hoped the Kärcher K7 would be the tool for the task.

Read on to see how it performed, then for more options, check out our guide to the best pressure washer.

Kärcher K7 Premium Smart Control pressure washer key product specs:

• Power type: 230–240V mains
• Max pressure: 180 bar
• Best for: getting the job done quickly – ground surfaces, vehicles and even garden furniture
• Hose length: 10m
• Power cord length: 5m
• Weight: 17.8kg

Getting started

My first impression of the pressure washer was just how heavy the box was. I had to get my partner to help me move it so I could start setting it up – an indication of the heavy duty product inside, maybe? Once we had taken it out of the box I was relieved to see it was on wheels and had a telescopic handle to move it around. 

As with a lot of appliances we’ve had recently, I was dismayed to see that the pressure washer came with five booklets of information. There is a separate instruction manual for the T7 Surface Cleaner accessory, in addition to one for the pressure washer, plus a safety manual, how-to guide and a product registration booklet. A lot of paper for a smart device, which also has step-by-step instructions on the Kärcher app. 

We started to set up the pressure washer by following the illustrated instructions. For my partner – who has used Kärcher products before – this was enough to help him, but I found that I definitely needed to look through the written instructions for clarification. After following the assembly instructions, the next step tells you to download the app and register your device. This is made even easier by scanning the two QR codes – one for finding the app for your phone model and one for registering the device. 

At this point I abandoned the written instructions as the app tells you how to continue set up (it starts right from the beginning, with assembly). Once you’ve paired your phone with the device – which is simple enough – you can then add what accessories you have, connect the water supply, turn the machine on and you’re ready to go.

One thing I would note is that the app doesn’t give you in-depth information on some aspects of set up and operation. For example, my partner pointed out that I would need to ensure that the hose was completely unwound from the hose reel before use – something the written instructions share. Lesson? You really should always read the instructions.

What is the Kärcher K7 Smart pressure washer like to use?

From the home screen of the Kärcher Home & Garden app you can choose out of nine options. The options are based on the different types of thing you might need to clean. The app then guides you through exactly what to do, step-by-step.

Cleaning stone floor areas

Seeing as the pressure washer comes with the T7 Surface Cleaner, I opted to tackle our brick driveway and stone garden patio. We have two children – a three-year-old and a six-month-old, so a lot of big jobs like this get left until the weekend, when we tend to do rock, paper, scissors for who looks after the kids and who does the jobs. It’s also a guarantee that whoever does the job, will end up with a little helper who is fascinated by new and noisy machines, especially one that shoots water!

I opted to start with the driveway and started to follow the app’s guidance on how to clean stone floor areas. We have quite a large driveway, so I decided to tackle it in sections as I wasn’t sure how long the detergent would last, or how long the task would take. The first screen shows you a summary of the pressure level, nozzle setting and how many steps there are (15 in this case). 

Spreading the detergent
The first step is to place detergent (if you have it), in the ’plug ‘n’ clean’ docking station. On the app (and bottle) it gives simplified instructions, so unless you’ve read the paper instructions, or watched a how-to video, it is not immediately clear that there are two caps you must remove before docking the detergent. You must then ensure the multi-jet lance is attached and is on detergent mode. You do this by twisting the head and the detergent symbol should show up on the LCD screen. There are two issues we found with this. The first is depending on how you have connected the multi-jet lance (there are two ways to put it in as the fitting is rectangular), when twisting the head, it’s not clear which setting you’re on. If connected one way, the correct setting is facing upwards on the lance. If connected the other way, it’s offset to one side. The other issue is the detergent setting on the LCD doesn’t immediately show up until you’ve pressed the start trigger. 

Once we had worked this out, I continued to follow the steps on the app. You select level 3 (the highest level) for detergent by using the plus button on the handle. Alternatively, you can select 'Transfer pressure to gun' on your phone and it automatically does this for you. You then wet the stonework, moving left to right and soapy suds should appear. It then advises to allow the detergent a bit of time to take effect. Using detergent helps lift the dirt but is not essential.

Using the T7 T-Racer Surface cleaner
After a quick coffee break, the next step was for attaching the T7 T-Racer. This is slightly different to the lance and again the app’s instructions are simplified. It’s worth noting that I would advise reading the instruction booklet for the T7 T-Racer too. Although 73 pages long (for other languages), the English instructions are less than three pages and contain vital information on its operation. As per the instruction booklet, I attached the T7 T-Racer and then returned to the app. You turn the dial on the head to the ‘hard’ position and it has two pedals – one for general surface cleaning and one for edges and corners. I selected the general surface cleaning and ensured the pressure was on level 3.

You then run the T7 T-Racer over the stone, keeping it moving. A tip on the app is to work in overlapping paths so no dirt residue is left in between. It has bristles underneath, so you may feel as if they’re there to be used like a scrubbing brush. However, the instruction booklet points out that is not to be used for scraping or scrubbing. You don’t have to exert any pressure as the rotating jet is extremely powerful and I could clearly see which bits I had done on the driveway. I found that if I moved the head too quickly, it left squiggly lines, so had to go over the same place more than once. Slow and steady movements are key. To do the edges of the drive and the corners, where the brickwork meets the house, I selected the edge and corner option, using the other pedal. This emits water from a nozzle at the front and the moss, cobwebs and weeds were no match.

Hosing down with the multi-jet lance
As the pressure washer was so powerful, quite a lot of dirt, sand and foliage was left sitting in puddles on the drive, but the last stage is using the multi-jet lance to rinse the stone. On the flat jet setting, with level 2 pressure, the app advises you to rinse the loosened dirt from left to right. As I was doing this, I noticed some areas where I could still see either the squiggly marks left by the T 7 T-Racer, or areas around the edges I’d missed. The spray from the lance is powerful enough to go over these small areas and remove the dirt, so your stonework is left looking spotless. 

Sweeping and finishing the job
Once you’ve finished, the final step on the app is to sweep up any soiling by hand. I think if you were to tackle a very large area all in one go, you might want to use a broom to sweep off some of the residue as you went along. I used ours a few times, when I noticed that the dirty water was sitting quite close to my neighbour’s drive.

Once I had finished the first section of the drive (took an hour and a half from setup to finish), my partner took over to do another section. It was lucky we did the drive in sections as the detergent ran out with about a third of our drive left to do. Luckily, the detergent is readily available from local hardware stores, or you can purchase it online. 

Once we had restocked the detergent (a couple of weeks later), we completed the drive and I moved on to the patio. Now I knew what I was doing, I whizzed through most the patio in about half an hour (the space is not much smaller than the drive) and used the final step with the multi-jet lance to do the stones around the top of the walls (our garden is multi-level). There is something extremely satisfying about a job like this, where results are visible straight away and once I had finished the main section of the patio, it showed up just how dirty the rest of the patio was.

Cleaning glass and other objects

After cleaning the patio, the pressure washer had kicked up some dirt which sullied the surrounding doors and windows. Following the instructions on the app for glass cleaning, I used the multi-jet lance on the flat setting to rinse the doors and windows. This setting can also be used to clean conservatories and green houses.  

Cleaning other objects
In addition to the areas I’ve already mentioned, the app has step-by-step instructions for pipe cleaning, cars, bicycles, wooden floor areas, stairs, motorcycles and facades. I will definitely be using the pressure washer to do our cars and the steps in the garden and have already bought some car cleaning detergent, ready for the job.

Is this pressure washer easy to use?

Once I had refreshed my memory, the pressure washer is very simple to assemble, operate and is extremely effective. It was only after I had completed the drive that I fully read the ‘How-to guide’, which I would recommend doing. Each page shows simplified instruction illustrations for areas to clean (which are not as helpful as the app), but there is a QR code to scan on each page which takes you to a relevant web page on the Karcher website, with an application video. This was very handy indeed and a quick way to get an idea of what to do or refresh your memory. And if you don't know how to use a pressure washer, the app guidance is much appreciated as you work.

One of the only issues my partner had when using the pressure washer, is he found the T7 T-Racer handle a bit too short. He is 6ft 4, so felt he was stooping to run it over the ground. He also found that the detergent spread better without using the multi-jet lance head. By removing the head, you get a wider spray which covers a larger area.

Additional features

The Karcher K 7 Premium Smart Control pressure washer has clearly been built with ease of use in mind. The plug ‘n’ clean option with the detergent is great, as it controls how much detergent is pulled through the machine, so you don’t have to do it manually. The telescopic handle makes transporting the machine easy and when you’ve finished with the machine and accessories, the integrated hose reel and onboard storage keeps everything tidy.

Does a pressure washer really need a smart app?

The app ensures you are ready to clean any object or surface, plus there are FAQs to check any issues and a link to the online shop, to see where you can buy detergent, or accessories. The step-by-step guidance is great for making sure you get the most out of your pressure washer and maximise the cleaning.

However there are a couple of fixes that could be made to the app itself. As we ran out of detergent when we tackled the drive, it was another two weeks before we attempted to finish the job. Following an early morning visit to B&Q for Karcher detergent, I then opened the app, ready to set up the power washer again. I had forgotten some of the setup instructions, such as how to connect the water supply, so I was hoping the app would provide this information. Unfortunately, it doesn’t, so I had to refer to the instruction manual. The other issue I found was that I had to reconnect my phone to the pressure washer and add on the accessories I had again. 

While doing this, I noticed that the app gives you instructions dependent on what accessories you have. Without the T7 T-Racer, the driveway can be done in nine steps, using just the lance. It also gives you options on how to do it without detergent. I do think the app could do with a few improvements, such as providing basic set up information and giving more detailed instructions on some parts. 

How does it rate online?

It’s not a surprise that this machine rates very highly, with most reviewers giving it five stars. Many commend it on how easy it is to use and what an effective job it does. Some complain that it is loud, but I would say it’s no noisier than some lawn mowers and I don’t feel as if it disturbed my neighbours.

Another positive point from many reviewers who compare it to other pressure washers, is how quickly is gets the job done, with some commenting that it takes half the time it usually takes them. So, not only are you paying extra for the app help, but for the added oomph, too.

As this pressure washer is Karcher’s most powerful and premium model, there is a large price tag to accompany it and it is the most expensive of Karcher’s machines. However, it doesn’t seem as if any other pressure washers on the market have smart technology and I would argue that it is worth every penny, due to how versatile and effective it is. I’m looking forward to what I can clean next! 

About this review and our reviewer

Bethan Davis works in PR for the tourism industry, but it currently on maternity leave after having her second child. She was sent the Kärcher K7 Premium Smart Control pressure washer in March 2021 and tested it over several weeks on her brick driveway and stone block patio.