Kärcher K7 Premium Smart Control review: power and performance on tap

I've reviewed a few Kärcher pressure washers now, the last being the Kärcher K4, and every time I do it is easy to see why they dominate T3's best pressure washers buying guide.

Kärcher not only have a the fundamentals of a quality pressure washer mastered, but the firm has also got a wide-range of them, too, with units for casual as well as more heavy duty applications.

The pressure washer I've reviewed here, the Kärcher K7 Premium Smart Control, is the maker's new flagship model and sits right at the most serious end of the home pressure washer spectrum. This is a very high powered pressure washer that delivers big power and plenty of features.

It also costs a pretty penny, too, so right here I hope to show if this is the right pressure washer for your needs.

Kärcher K7 Premium Smart Control review: price and what you get

In terms of pricing and availability, the Kärcher K7 Premium Smart Control is available now and costs a touch over £500 at the time of writing. This is the most expensive pressure washer that Kärcher makes, comparing to the Kärcher K4's price of around £350 and the Kärcher K2's price point of just over £100, to name but a few models in the range.

To be very clear here, right at the start of the review, this is flagship pressure washer that offers massive cleaning power and performance, but I would say that only those with big cleaning needs and/or large homes with plenty of patio and/or decking will likely need it. If you need to clean a lot of vehicles this will also likely be a good fit.

Open the Kärcher K7 box and you're greeted with the pressure washer itself, a long with its instruction manual, documentation, Smart Control gun, 3-in-1 Multi Jet spray wand, T7 Plus Patio Cleaner, wand extender and stone and façade detergent.

The Kärcher K7 comes with a 10m High Pressure hose line, too, which neatly on this model is stored on a rear-mounted cable wheel. This cable then extends (like most Kärcher models) through a hole in the casing so that it comes out of the pressure washer from the front.

Assembly is straight forward. You first plug the High Pressure cable into the Smart Control gun, which simply clicks into the handle. Once that is achieved you plug your hose into the water-in port on the Kärcher K7, then plug in the pressure washer's power cable, add the detergent bottle to the detergent port, attach either the Multi Jet spray wand or T7 Plus Patio Cleaner (via extender lance) to the gun and flick the power dial to on.

One of the main issues most serious pressure washers have is how cumbersome they are to move, and while the Kärcher K7 is no exception, it's rear mounted cable reel really makes cable management much easier. With three different cables on the go at all times (power, water and hose) anything that makes it easier to use and move the pressure washer is to be welcomed.

Not all models of Kärcher pressure washer come with this reel, so this is definitely a plus point to buy.

As with other Kärcher pressure washers, the design of the K7 is very functional, with multiple storage bays and clips on the chassis allowing you to store most of its wands, lances, gun, and cables neatly on it. There is an elastic net mesh that I always use to store the wound up power cable on the rear, while as with most more heavy duty pressure washers you get a brace of large plastic wheels for movement.

Being candid, though, the Kärcher K7 is not easy to move and it is heavy. We're talking 17.8 kg heavy and as the wheels are linear in their movement with no rotation available, moving the pressure washer around (and especially with all its cables attached) is a pain. I ended up just picking it up and dropping it down where I wanted most often, rather than wheeling it. But I realise not every user will have the strength to do that.

This is a serious and powerful pressure washer, though, and its weight shows that.

Kärcher K7 Premium Smart Control review: power and performance

So, yes, be under no illusion, this is the biggest and most heavy duty commercial pressure washer Kärcher makes. It delivers a maximum pressure of 18bar/MPa and a maximum flow rate of 600l/h, while its power rating is 2.8kW. Area performance rests at 60m²/h, too, so when you power this pressure washer up you can clean anything.

Indeed, if I was to say why you should buy this pressure washer immediately if you can afford it is that you will never need to buy another unit ever again, as there is no application where its power will be left wanting. Patios, cars, walls, windows, cycles, motorbikes, decking, fences, driveways – you name it, the Kärcher K7 will clean it.

Check out its performance in the video below cleaning my patio.

The fact that it comes with a Multi Jet spray wand and a T7 Patio Cleaner means you've got options in how you clean, too, and both deliver excellent results. I used both the Multi Jet and T7 on my patio, with and without detergent added, and both cleaned excellently.

The T7 will appeal to those who want to keep off spray down to a minimum, as it contains most of the action under it, while the Multi Jet wand means you can vary the strength and spread of spray from the gun by simply rotating it. The extender tool can be used with both T7 and the Multi Jet as well, meaning that the user can stand straight and not have to bend down to make optimum connection.

The Kärcher K7 Premium Smart Control is the latest version of the Kärcher K7, and one of its new sells is that you can connect the washer to your phone via bluetooth to control the trigger gun. This app shows you different pressure settings and also helps the user control the amount of detergent to use. It's a neat extra, but I think most users will likely use the system manually without connection – and that's no bad thing as the Kärcher K7 makes controlling how you clean very easy on its own.

The Plug and Clean detergent system remains as easy to use as ever. You simply take the cap off the detergent bottle and then turn it upside down and slot it into the detergent port (which is recessed) on the top of the pressure washer. The detergent I used on test is the one that came with the Kärcher K7, the Stone and Facade cleaner, which is designed for use on patios and decking.

Can you clean without detergent? Absolutely, but the ease of dirt removal is enhanced by its inclusion.

Naturally, for a system that advertises itself on its versatility, I also tested the Kärcher K7's ability to clean my car. While I would say that exterior surface cleaning is a pressure washer's primary reason to exist, at least in terms of my usage history, that is something that gets done a handful of times each year. Cleaning my car, cycle or motorbike though happens once a month or so, though.

And, as you would expect from such a powerful pressure washer with variable cleaning pressures and modes, the Kärcher K7 made getting my auto spanky easy, and especially hard to clean areas like wheel alloys. Check the video out below for a short example of the action.

And, on that note, it is important to mention that Kärcher understands this, and sells multiple different detergents. So, on top of the stone and decking detergent, the maker also sells a universal cleaning detergent as well as a ultra foam cleaner that is ideal for cleaning vehicles. There's plenty more, too, such as a plastic cleaner, wood cleaner and even a 3-in-1 car shampoo detergent.

Most of these detergent bottles cost just under a tenner, and I would advise anyone who picks up a Kärcher pressure washer with detergent port to invest in a few bottles, as it just makes getting optimal results even easier.

Kärcher K7 Premium Smart Control review: verdict

Overall, then, it is impossible not to be impressed with the Kärcher K7 Premium Smart Control. Guess what, a flagship pressure washer from one of, if not the, best pressure washer maker in the world is more than a bit good.

From the fit-and-finish of the K7's chassis and accessories, to the high powered cleaning on offer, and onto the versatility it brings in what and how you clean, this is a pressure washer that really goes the distance. If you ring it up I guarantee you will not be disappointed.

However, after using some of Kärchers other pressure washers, I can't help but come away from this Kärcher K7 Premium Smart Control review thinking that it is likely too much pressure washer for most people. Look, if you can spend half a grand on a pressure washer then this is absolutely one of the models you should look at, but the truth is that you'd need big cleaning needs in order to fully justify it.

Personally, I think that a unit like the Kärcher K4 or K3 will be a better fit for most people, who just want to clean their car or bike every now and then, as well as do some moderate exterior cleaning a few times a year. And both of those systems cost markedly less than the K7. So, all I'm saying is that you should carefully consider your cleaning needs before pulling the trigger.

For those who want a no-compromise cleaning solution, though, then the Kärcher K7 Premium Smart Control is a fantastic choice. It's the flagship pressure washer Kärcher makes and it delivers flagship performance. As such, I find it impossible not to recommend.

• When your patio is clean, why not put one of the best pizza ovens on it?