Kärcher K7 Premium Smart Control Home pressure washer review

The Kärcher K7 Premium Smart Control Home pressure washer is widely considered to be one of the best premium pressure washers available. As such, I was very excited to try it out.

In summary, this is an amazing pressure washer, with obvious high build quality and I have no doubt it will meet every domestic application it’s suitable for with ease. In fact, one of the main criticisms of this washer is that it’s probably more capable than most people will ever need

The Smart Control is a little gimmicky, but the guidance is useful and clear, and the ability to transfer the required settings worked flawlessly. As the top of the range Home and Garden pressure washer, it’s expensive, but if your property has large patio or decking areas, or expanses of rendered walls, or a small fleet of cars on the driveway, then it will pay for itself in the time it saves, every time you use it.

Find out how the Kärcher K7 Premium Smart Control Home pressure washer performed on a patio, car and other surfaces, then check out more options in our buying guide to the best pressure washers. 

Getting started with the Kärcher K7 Premium Smart Control Home pressure washer

As a seasoned pressure washer user, my first surprise was how heavy the box was. As shipped, it’s 25.9kg, with the pressure washer alone coming in at 17.8kg. 

Unboxing was straightforward, and although some minor assembly is required before use, the Kärcher Home and Garden app (available on iPhone or Android) clearly walks you through the steps, culminating in making a Bluetooth connection with your device and explaining the various parts of the machine and its controls.

Connection is straightforward: plug the power lead into an RCD protected socket, connect your hose to the front of the pressure washer, and you’re ready to clean.

What is it like to use?

So down to business, starting with the 3-in-1 multi-jet spray lance with three spray types. This is an interesting design where your choice of the three available spray types is selected by twisting the lance.

For the flat stream nozzle, this combines with three areas of application (SOFT, MEDIUM, HARD), each with two pressure levels effectively letting you select the force of the water jet in six increments. This makes the flat stream nozzle suitable for a range of cleaning tasks from sandstone and delicate garden furniture, through cars and bikes, all the way to the toughest stone. And for particularly stubborn dirt on hard materials, the dirt grinder nozzle used with one of the two HARD settings is perfect.

The last setting, the mix mode, is used in conjunction with a Plug 'n' Clean detergent bottle. Rather than setting a pressure for the jet, this allows you to set three levels or ratios of water to detergent mix. While there are a wide-range of Kärcher detergents available for specific purposes, the bottles do appear to be refillable if you have a particular favourite car shampoo or stone cleaning formula.

And here’s where the Smart Control feature comes in. Figuring out which mode to use and at what pressure might be straightforward for some experienced users, but if you’re not sure, the iPhone or Android app can help you to make the right choice.

When asked “What would you like to clean next?” choose an appropriate icon or tap the three dots to see the full list (Car, Pipe cleaning, Facades, Stone wall, Motorcycle, Stairs, Wood floor areas, Stone floor areas, Bicycle, or Glass cleaning - such as for a conservatory).

The Application Consultant will then suggest the ideal pressure level and you can transfer that automatically to the device if you choose, although you can set it manually using the + and - buttons. You can also review the ideal process where suggested consumables and accessories will be listed along with the pressure level, lance setting, and the number of steps in the process. Clicking view steps takes you step by step through what to do with clear photos and textual descriptions.

The last part of the package to mention is the T-Racer Surface Cleaner attachment with 0.4m extension for patio and deck cleaning. Two peddles allow you to select surface cleaning or edge and corner cleaning, and a knob on the top can be turned from a HARD to a SOFT setting which lowers or raises the rotating jets underneath.

How does it perform?

CLEANING A CAR 

I started with car cleaning. I normally use snow foam on our cars but didn’t have the attachment for the Kärcher K7, so I was only able to test an initial wet-down and removing the snow foam (after it was applied with an alternative pressure washer), but it performed superbly. 

I’m used to having to move a pressure washer around the car when in use, but the 10m hose length let me reach all the panels of the car without having to move it once, a big plus given the size and weight of the machine. I used the app on the phone to select my application and to transfer the settings, so all I needed to do was to twist the spray lance round to the flat stream nozzle and pull the trigger.

CLEANING THE PATIO/SLABS

Our patio and steps are black Indian limestone and so would be fine with the recommended HARD setting. The app, knowing I had the T-Racer Surface Cleaner, suggested that I should use that, so I started there, attaching it to the high pressure gun, transferring the settings once again, making sure the peddle for surface cleaning was engaged and setting the knob to the HARD setting.

I’ve used patio cleaning attachments before on both Kärcher and competitor pressure washers, and so I wasn’t expecting much, but the T-Racer is a cut above the others. It was easy to move and cleaned both efficiently and quickly – much quicker than I’d experienced before. I’d conservatively say it cut the time in half. 

However, there was a small issue. My patio and steps are edged with slate chippings and as soon as the T-Racer came into contact with these edges, it lifted up some of the chippings and you could hear them spinning around underneath. There’s no stone guard underneath like some other models, so you do need to be careful of this, both in the potential for the stones to be ejected at force where you might not want them to be, but also because of the clear damage they did to the rotating jets. 

That aside, the overall performance was excellent, although the edge and corner setting not so much.

I also tried both the flat stream nozzle and the dirt grinder on the same area. To be honest, based on previous experience with standard and dirt blaster nozzles, I expected the dirt grinder to be more powerful, but to be slower in use than the flat stream nozzle, but that wasn’t the case at all. Not only did the dirt blaster nozzle perform better in cleaning the surface, it seemed to clean a larger area more quickly that the flat stream nozzle. Given that, I successfully switched my method to using the dirt grinder for the sides and corners, and the T-Racer for the rest.

While all the power is great from a cleaning perspective, I did have issues with the grouting used between our slabs. We use a permeable resin grouting, and where this wasn’t wholly contained (such as at the edges of the slabs where they border the slate chippings) some of this was removed.

This isn’t necessarily an issue with the pressure washing, but it does remind you that suggested settings can’t cover all scenarios and are simply that, suggested – you need to apply your own common sense sometimes and I was able to change my approach to minimise this particular issue.

About this review and our reviewer

Garry is an independent product tester, bringing decades of skill and experience in multiple trades to the art of authentic, real-world reviews. A technology geek, tool addict, and soon-to-be Passivhaus self-builder, he lives with his family in Worcestershire.

Garry put the power washer through its paces and tested its settings on slabs and patio surfaces as well as his car to get a good idea of its strengths and weaknesses.

We are not given any payment by Kärcher for our reviews, but may be allowed to keep the product, meaning we can test it over a greater length of time, and update this review if required.