Pressure washing your bike is a pretty bad idea because the water will force its way into your bearings and bushes and other important nuggets. Then over the space of a few rides the water in the bearings will emulsify with the grease and eventually all the grease will just run out of the bearing which will wear out quite quickly after that.
I know a guy who worked at a petrol station - so he got free tokens for the car pressure washer - and all the bearings went in his Ironsorse Sunday in about 3 weeks because he used the pressure wash after every ride.
I just use a hose pipe with some sponges and brushes.
But if you haven't got anything else than a pressure washer, just stand way back from your bike when you use it and everything'll be reet