Pressure washers are not a good way to start for a
DIY watermaker. The pumps (even with ceramic plungers) do not
work with
salt water well, corrode and need to be replaced often. They are incredibly noisy. The AC motors are low cost and inefficient and mounting the pump on a standard heavy duty
motor is not straightforward. Search the web, the topic has been discussed at length. I advise against it.
You are much better off with a
cheap AR pump and a matching DC
motor. If you still want to
experiment with pressure washers, Karcher is a good way to go as their pumps are mostly plastic but again, it will be a waste of time at the end.
One consideration for
DIY watermaker is to decide from the start if you want to make potable
water (for drinking and cooking) or just fresh water for
cleaning,
laundry and bathing. The potable water
route requires potable hoses, pumps, fittings... it is a higher standard and by the time you source all the
parts you will be better off
buying one of the kits from ebay or the
Cruise RO. Alternatively, you buy
drinking water as most of us do at home anyway (2.5 gallon containers
work really well) and use the watermaker for the other needs. In any case, you need to bring as much
beer as mineral water, so it is not so bad.