High pressure water is an effective cleaning agent for many surfaces, particularly masonry such as bricks, driveways, sidewalks, and patios. High pressure water literally blasts away dirt, mildew and other contaminants.

However, painted surfaces should generally not be cleaned with high pressure water. Not only can such a method cause damage to the paint and the underlying substrate, it is ineffective in removing dirt and mildew on such surfaces.

A wide variety of pressure washers are available. Their output can range from 1,000 PSI to 5,000 PSI. Machines with outputs above 5,000 PSI are generally considered water blasters, and are usually used for industrial applications.

For most residential applications, an output of 1,500 PSI to 2,500 PSI is sufficient.

The output of the pressure washer is controlled and directed with a gun and wand assembly similar to that found at a self-service car wash. A tip at the end of the wand shapes the output into a fan, the width of which can be changed by inserting a different tip.

Though masonry surfaces are less susceptible to damage from high pressure water, care must be exercised. Pressurized water is abrasive, and prolonged exposure can loosen pea gravel and mortar.

In many situations, pressure washing may not sufficiently clean a surface. Bricks, for example, are highly porous and mildew and algae can grow in these pores. In such situations, a diluted bleach solution may be required to remove the residual fungal growth.