If needed, water run-off from your pressure washer can be easily collected and safely disposed of in gardens or lawns.
The cheapest and easiest way is to place a few shovelfuls of play pit or beach sand in a polypropylene sugar or potato bag and place that in the lowest spot where the water will run, like next to the curb or over a sump, for instance.
Using a 15 Gallon Wet-Vac, and powering it with a small generator, will suck up the water. Dilute it down and dispose of it as ‘graywater’. Ideally, all professional graffiti removal contractors should have this set up available.
Unlike other commercial hard surface cleaning such as pressure washing pavements, graffiti removal uses very little water.
In fact the pressure washer is used as a quick release rinse only of dissolved or softened graffiti. This means there is far less water to worry about in comparison to general power washing chores.