Positive Flow

You can run your pressure washer directly from a tap, this is called positive flow. The only problem with this method is that when you are using a powerful machine, the water supply you are drawing off may not be able to supply your pressure washer with water fast enough.

Negative Flow

With my petrol-driven pressure washer I have a suction hose on it that has a filter on the end. I also have an old plastic chemical barrel that I can wheel around on a trolley. The chemical barrel acts as my buffer tank between the pressure washer and the water supply.

I run a hose from the tap into my barrel, let the water fill it up a bit, then connect my suction hose to my pressure washer and fully submerge the filter on the end into the barrels water.

Next I turn my pressure washer on and the water gets sucked up through the filter, up the suction hose and then into my machine.

When I've finished pressure washing the surface I intended to clean, I just tip the chemical barrel on its side and let the water run down a drain.

The disadvantages with this method are that you might accidentally let your buffer tank run dry. Wheeling the buffer tank around can be difficult if it gets filled too high because water is very heavy. Also, I’ve read using negative flow can lead to premature oil seal wear on your pump??