Buyers compare pumps. Owners live with connectors.
The four systems
Kärcher bayonet — the largest domestic accessory range, entirely proprietary. Nilfisk Click&Clean — its own smaller ecosystem. Bosch — its own connector, with listings that name compatible machines. M22 thread — the trade standard, used by Kränzle, Scheppach, most petrol machines and much of the accessory market.
What it costs to get wrong
A surface cleaner, a drain hose, a foam cannon and a brush over five years easily exceed the price of an entry machine. Bought for the wrong fitting, they are decorations.
The M22 trap within the trap
M22 comes in male and female, and in 14 mm and 15 mm (0.59 in) insert sizes that look identical and do not seal against each other. A joint that leaks while fully tight is usually mismatched inserts, not a faulty part.
The practical rule
Decide which accessories you will realistically want — a surface cleaner, at minimum — and check they exist in the machine’s native fitting before you buy the machine.
The questions we hear
Which fitting should I prefer?
M22, if you expect to keep accessories across machines — it is the trade standard and the widest accessory market. Kärcher's bayonet has the largest domestic range but ties you to one brand. Neither is wrong; choosing without knowing is.
Are adapters an acceptable answer?
One is. It is a joint at the highest-pressure point in the system, so it must be rated above the machine's peak, fully seated and checked for weeping. Two in series is a repair waiting to happen mid-job.
Last reviewed 2026-08-15