On Sun, 01 Apr 2012 16:13:06 +0100
Hugo Nebula wrote:

[Default] On Sun, 01 Apr 2012 16:03:42 +0100, a certain chimpanzee,
Lobster , randomly hit the keyboard
and wrote:

There's certainly no need for them to shift vast volumes of water to
be effective. I think the point is that they generate (or should do)
a very high pressure by pumping water through a very small orifice.
Certainly my Karcher blasts out a very effective jet, but the actual
flow rate is way less than provided by a mains-fed tap.

So would a hose with a small nozzle not achieve the same effect?

No, because you can't generate more pressure than you start with
without some extra force, such as a pump.
--
Davey.