Karcher K4 Pressure Washer Review

Fox Morgan tested the Karcher K4 pressure washer to clean up a filthy boat bottom and a load of other filthy things. Does this live up to the hype? Spoiler alert, is blooming brilliant.

Karcher K4 Power Control Pressure Washer

This Karcher K4 Pressure washer is a dirty/clean little pleasure.
Did you know that scrubbing the bottom of boats is a form of therapy to me? I don’t know about you, but I love pressure washing stuff. It can be some dirty fencing, grubby flag stones, or a weedy or barnacle potted boat bottom.

Let’s have at it with a pressure washer. Seeing the dirt blast away is incredibly satisfying. This Karcher K4 pressure washer comes with multiple pressure levels of satisfaction.

Because as you might have gathered I like to pressure wash everything I conceive as being pressure washable. Horse rugs? Yes. Old heavy duty tarps? Yes. My boat decks? Yes. Manky cockpit teak? Yes I know I’m an absolute barbarian.  And on it goes.

Pressure washers are notoriously prone to being used on things they really shouldn’t. That high pressure might satisfactorily blast away green grime, but it might also blast away any structural integrity of the canvas or fibres of the fabric/wood you’re cleaning.  This is where you need a pressure washer where you can use a lower pressure setting…

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Step up then, the Karcher K4 pressure washer.

Pressure (bar/MPa) 20 – max. 130 / 2 – max. 13
Flow Rate max. 420 l/h
Power rating 1.8Kw
Power Cable 5m
High-pressure gun: G 160 Q Power Control Gun
Vario Power spray lance
Dirt Blaster spray lance
High-pressure hose: 8 m
Detergent application via: Plug and Clean system
Telescopic handle
Water-cooled motor
Integrated water filter
Adapter garden hose A3/4″
Weight without accessories – 11.5kg
Dimensions (L × W × H) 402mm x 306mm x 588mm

This Karcher K4 pressure washer has three, yes three levels of pressure adjustment for a range of items. So rather than just holding the wand a bit further away and hoping for the best, with this one, you can really get in there accurately and not blast the thing you’re cleaning to smithereens.

There’s lots of really nicely designed elements to this one. I love the extending handle which allows it to be easily wheeled about, but it tucks away back in my van or car boot easily with the handle stowed.

The lance and wand storage is robust and allows the tools and attachments to be neatly stored onboard the unit. I especially like the bit of netting over the back (see pictures in gallery) which is a really handy place to stash bits.

The high pressure hose attachment is a sturdy metal quick release click in under the hose stowage hanger and the low pressure water inlet is the standard screw fit attachment for a clicklock hose fitting or other fitting of your choice. it comes with the hoselock fitting as standard but the thread is compatible with more heavy duty metal fasteners.

When I first unpacked this pressure washer, I struggled to get the high pressure oscillating nozzle to  function. I had to disassemble it and inspect. I found a tiny burr of plastic that was stopping the cone from spinning internally. Once removed and the nozzle reassembled, it was blasting the barnacles off in seconds.

An optional extra that didn’t come with mine is the soap bottle. I have a soap bottle on one of my other pressure washers and they are surprisingly very useful, especially on a lower power setting for cleaning canvas canopies and other exterior fabrics, such as a dodgers and winter covers.

Along with the scrubbing brush, used on the lowest pressure setting this Karcher K4 is pretty much the multitool of cleaning.

This is by far the best pressure washer I own, or have ever owned as it happens and I’ve had quite a few over the years.

I love mine. I love it even more because my dad bought it for me. It’s the gift that keeps on giving.

If you want to read about more pressure washers that we have tested, then have a look at our other article: Best pressure washers for boats






  • adjustable power, good build quality, comes with good range of tools as standard


  • larger and heavier than a lower priced/lower specified pressure washer, premium price tag

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