Karcher K4 Pressure Washer Review
Renowned for their outstanding performance and design combinations in the world of pressure washers, the Karcher K4 is a model that sits in the middle of the line-up. Smaller, lighter, yet yielding a water cooled motor (delivers 1900 PSI/130bar) which normally appears in their higher up models, this particular flavour is the £399 ‘Premium Power Control Car & Home’ bundle, which includes 2x bottles of cleaning solution that the washer auto-mixes, and a plethora of tools to tackle anything from cars to decking. Is it actually the perfect all rounder?
Design
The boxed washer will be in parts ready to be assembled upon first greeting it. This is a relatively easy setup process thanks to the Karcher app briefing through each step of assembly.
Once assembled, its bright yellow appearance claims the brand’s aesthetic at just a glance, but whilst it may look cheery, we were able to determine during our testing that the plastics used to armour the outer body of the Karcher K4 are rather hardy on a variety of cleaning duties. This instills confidence in its long-term usage where it may well receive repeated bumps and scrapes against our granite walls, which the body just shrugs off.
The functionality is all well considered. A front water inlet can be used both directly from a running tap or draw its own water from a water butt using the Kärcher suction hose and filter. There’s storage for one lance tool and snow foam nozzle on the Karcher K4 unit, however the bundled rotating washing brush, T5 surface cleaner for patios/decking and two bottles of cleaning detergent cannot be housed on the unit. There is an integrated 10m hose reel, which makes storage so much easier to deal with (power cable also wraps around).
Usability
Most of the interaction with the product will be via the Karcher G 160 Q Power Control Gun, this is where either the Vario Power spray lance or Dirt Blaster spray lance connect via the quick-connect system which is simple to get going - just a push and a turn. The chunky and solid design of the gun feels positive in hand and the trigger is nice and clicky. An LED display conveys the level of water pressure being blasted from level 0-3, and all attachments can be adjusted so you can achieve the desired level of water pressure.
The K4 has a significantly lighter 12kg design over the behemoth 16.8kg K7, making it a manageable unit to carry up steps and onto different levels. Additionally the unit is equipped with a practical telescopic handle and large wheels, which make the washer an easy affair to manoeuvre over flat surfaces and store away. Despite being a bit lighter than other Karcher models, its centre of gravity is better placed than our previous Nilfisk washer, which would regularly tumble over on inclines from a mild tug on the hose when fully extended. This is another thing we like about the K4; the 10m length of retractable hose offers more than enough freedom to climb walls and clean areas where your main water hose inlet or power lead won’t allow, but for closer jobs we can unwind just the length required.
Cleaning performance
Decking: Our Envirobuild decked boardwalk style pathway and Millboard decking area haven’t been in receipt of a clean since installation last summer and we were keen to give both a wash. Interestingly we couldn’t note any build-up of algae along most of the pathway, with the exception of parts which were nearer trees, and the real issue was a build-up of general dirt. However, the Millboard decking area was covered in algae, to such an extent it camouflaged the original limed oak colour.
We started off by using the supplied Karcher patio detergent, via the Plug 'n' Clean system on top of the K4 pressure washer. This is an incredibly convenient and impressive implementation of an auto mix feature; it really does just work without any additional setup. On the LED display you’ll know if the adjustment of the lance is set to initiate auto-mix to dispense a visible white cleaning agent. It’s not a power wash output but more of a rinse. Next we swapped the Vario Power spray lance for the T5 T-Racer surface cleaner, with some doubt as to how this spinning tool would perform based on previous experiences with similar pressure washer accessories that end up being time impeding novelties. To our delight and surprise, the surface of each composite decking board was being cleaned in a matter of a few passes, and we weren’t getting wet because the water splashing is retained within the T5 unit. This is a much quicker method over using the lance, which was the necessary case with our Nilfisk washer on our other composite decking areas, so the Karcher K4 has put it into retirement. Whilst the T5 surface cleaner is an excellent tool, it doesn’t clean around 2 cm away from edges where there’s a wall in our instance. So after using the T5 we headed back along the pathway and decking perimeter with the Dirt Blaster spray lance to tackle the edges with immense spiralled pressure, doing so in just one pass. This resulted in a glisteningly clean composite pathway and decking area, all quickly restored to their original appearance on installation a year ago.
Car: Using auto-mix is no doubt a particularly useful feature for decking, patios and the like with the appropriate detergent. For vehicles, however, when used with the lance tools, it produces soapy suds which are fine for a contact wash and more akin to a wash and wax style clean. If you are looking for a wash that leans more into the contactless sphere, that’s where the supplied Karcher snow foam nozzle comes into play. We generally use this mode as it means the least contact possible when cleaning vehicles, avoiding unintentional damage to the clear coat. Of course, the occasional spots will need elbow grease but generally most of the car will not need direct contact. You can use the same supplied Karcher 3-in-1 car shampoo detergent to either fill the 300ml bottle or even attach the entire Karcher supplied detergent bottle for a larger reservoir to work with. It’s a good starter snow foam lance accessory and competent in delivering thick soap studs that stick then slowly run along the paintwork to loosen dirt; it also waxes the car at the same time. Furthermore, when rinsing off we noticed the consistent focused spray pattern style offered by the adjustable Vario Power spray lance (set to car) is very effective in dislodging tougher grime and dirt from the body, glass and alloys. The entire process using the Karcher K4 resulted in a universally clean car, that had a brilliant shine with no visible dirt or stains.
Verdict
An upper mid-tier level pressure washer entry that isn’t in any way watered down in power or functionality. The Karcher K4 ‘Premium Power Control Car & Home’ is a formidable cleaning companion that combines sleek design, user-friendly features such as the controller’s LED display and auto-mix, and showed impressively speedy cleaning performance on our boardwalk style composite decking/pathway. It offers overall top value through the bundle of useful and well made accessories for car and home.
