I don't own a Karcher pressure washer: but I know a man who does, and since it's my dad, I can borrow it whenever I go over to visit for a cup of tea. <g>

My dad was in the tools and hardware business, so bought this some years ago, at trade prices, and it has seen a fair bit of use over the past 10 years, which is encouraging for those who have just purchased!

The only hiccup has been the adjustable lance that you pull back to turn detergent suck on, or push out for high pressure. The brass has corroded a little over the years, and it needs persuading with something heavy to change position. That said, it still operates despite the abuse.

We have used the tool for all sorts of tasks: patio and drive cleaning most frequently, but also with a rotary [water powered] brush to clean greenhouse and conservatory roofs, and in one ill fated experiment to wash an old car with the rotary brush AND cleaning chemicals.

The car had been treated with turtle wax colour restorer, and as I washed it, the runoff was an interesting dirty red colour, while the car was returned to its natural faded shade of red [but at least clean!]. The car was subsequently retreated with colour restorer, and sold. . . .
If you bought it, I'm sorry!

Additional equipment purchased for the Karcher included a drain rodding attachment- 15 metres [30 was also available] of tube with a rodding nozzle on the end: one forward clearing jet, and three rear angled driving and clensing jets, to push the tube forward, and flush the debris.

This has been a great success on a couple of occasions, once clearing a load of detergent buildup that had blocked a pipe, and another time fat buildup and grit that the kids had deposited. This amply repaid the cost of the attachment, besides not having to wait in for dynorod.

Splashback can be a problem if you are not careful- I once had to wash down a manhole chamber after clearing a blo
ckage, and managed to blow back a faceful of untreated sewage when the jet hit the step- be warned!

To sum up: heavy, noisy, need to watch what you are doing, modern models are cheaper

but

effective, efficient, powerful, adaptable, reliable, plenty of tools still available