It is very important to keep your water clean.  Your feed water supply is a good place to start by installing a low pressure filter before the  pressure washer.  Quite often a filter on the inlet is not enough.  A small piece of dirt picked up by a coupling on your high pressure hose, wand or other accessory can wreak havoc with your nozzle or mult-nozzles.

Solution..... a high pressure filter is small and very effective in stopping dirt from plugging up the nozzles on your wand, surface cleaner or water broom.

These are easy to install and clean.  You can put them anywhere in the high pressure side but usually they are installed as close to the nozzle/s as possible