The machine everyone starts with · review
The first Kärcher that publishes its flow rate — and the number that tells you what the machine will actually do.
The bottom line The sensible middle of the range: the first model in the family where the specification tells you what you are buying.
The K 4 FJ Home is where the Kärcher range starts publishing the figure that matters. 420 l/h at up to 130 bar, with a stated 30 m²/h area performance and a 5.7 kg body — four numbers, all from the manufacturer, and enough to compare the machine honestly against anything else in the class.
The temptation with pressure washers is to buy bar. Bar breaks the bond between dirt and surface; litres per hour then carry that dirt off the surface and away. A machine with plenty of pressure and little flow cleans in narrow, slow, striped passes — which is why two machines quoted at similar pressures can differ by half an hour on the same terrace.
The ten bar between this machine and the K 3 changes almost nothing. The published flow figure and the larger T 5 surface cleaner in the box change a great deal.
Beyond the T 5 head, the box includes the Foam Jet nozzle and — less obviously useful until you need it — a detergent suction hose. The foam nozzle draws from its own small bottle, which is convenient for a car and limiting for a terrace; the suction hose lets the machine draw straight from a five-litre container of patio treatment instead. On a large area that is the difference between refilling four times and not stopping.
There is also a water filter on the inlet. It is a small transparent thing that people ignore until the machine loses pressure, at which point it is almost always the answer — particularly on well water or after work on the mains has stirred up the pipes.
At 5.7 kg this is easy to carry to the far end of a garden and easy to pull over by tugging the hose. Kärcher’s own answer is the hose reel and the fixed handle on the larger models; here the practical answer is simply to move the machine more often rather than dragging its hose.
A single Amazon reference covers Germany, the UK, France, Italy and Spain — the same machine, the same accessories and the same spares in all five. It is not listed on Amazon’s US store.
| Maximum pressure | 130 bar |
|---|---|
| Flow rate | 420 l/h |
| Area performance | 30 m²/h |
| Weight | 5.7 kg |
| Included | T 5 surface cleaner, Foam Jet nozzle, dirt blaster, Vario Power lance, detergent suction hose, water filter |
| Part number | 16795620 |
| Amazon reference | B0DQ8HGD2P |
| EAN | 4066529155894 |
The pressure difference is ten bar, which is nothing. The difference that counts is that this machine publishes 420 l/h and the K 3 publishes no flow figure at all, and that it ships with the larger T 5 head rather than the T 1. Flow is what carries dirt away once pressure has lifted it, so on a large terrace the K 4 finishes noticeably sooner.
It is the manufacturer's figure for area covered in an hour, and it assumes the surface cleaner is fitted and the dirt is ordinary. Treat it as a comparison number between models rather than a promise about your own terrace: heavy lichen on old stone can halve it, and a hand-held lance rather than the surface head halves it again.
No pressure washer should be. Any water left in the pump expands when it freezes and cracks the housing, which is the single most common way these machines die — and it is not a warranty repair. Drain it, run it dry for a couple of seconds and store it above freezing.
140 bar · 450 l/h · 2 100 W · integrated storage
The Bosch that finally publishes a flow rate — 450 l/h, which is what the UniversalAquatak machines never gave you.
Best for: A drive, a terrace and vehicles, for someone already inside the Bosch accessory system
≈ £235 / 200 €
125 bar · 3-in-1 nozzle · 5 m hose
The cheapest machine here, and the one whose single nozzle does the work of three.
Best for: A first pressure washer for a small garden, a bike and a car, where price decides
≈ £135 / 97 €
135 bar · 3-in-1 nozzle · 7 m hose
The 125 with ten more bar and two more metres of hose — and the second of those is the one you notice.
Best for: A drive, a terrace and a car — the general-purpose choice where the 125's hose would be the limiting factor
≈ £115 / 140 €
