How a Pressure Washer Works

A pressure washer forces water through a small opening to create pressure and cleaning power. This process is analogous to putting your finger over the opening of a garden hose to increase the pressure.

But a pressure washer takes this process a little further. Instead of using the 40 pounds per square inch (psi) of a standard garden hose, a pressure washer increases the pressure to more than 8000 psi.

The force behind that pressure comes from a water pump driven by a fuel-powered engine, an electric motor, or pneumatic (air) pressure. Once the pressure washer is started, water enters the pump and is forced through a high-pressure hose that leads to a spray gun. The pressurized water exits through a metal nozzle attached to the spray gun.

Key Components

Water pump:

This is the heart of a pressure washer and generates the machines' cleaning power. The pumps rely on either fuel-powered engines or electric-powered motors.

Fuel-powered engines:

Generally the choice for outdoor use, gas, diesel, kerosene and propane -powered engines are good options. In addition, machines powered by these engines are mobile because they don't need to be tethered to an electrical outlet.

Electric-powered motor:

More compact than fuel-powered engines, these motors generate no fumes and are ideal for indoor applications.

Heating units:

These components typically heat cold water using kerosene, diesel, or heating oil. But because these products produce exhaust, their use indoors is limited. For indoor use, consider an electrical-, propane- or natural gas-heated unit.

High-pressure hose:

Hoses are generally constructed of wire-reinforced rubber designed to withstand water pressures more than 125 times the pressure of a standard garden hose. Hoses designed for the highest pressures, commonly have two layers of wire reinforcing. The hoses are covered with rubber or thermoplastic -- opt for rubber whenever possible. Some hoses are designated as 'non-marking," which means if you drag them around a facility, they won't leave marks on floors, walls, etc.


Pressure washer nozzles typically come in variety spray patterns.

  • > 0º produces the thinnest stream and highest impact on the smallest area. This is the nozzle for the toughest jobs.
  • > 15º creates a small fan pattern and is ideal for jobs like removing paint and old finishing.
  • > 25º yields a wider fan pattern and is designed for washing and cleaning debris on the ground.
  • > 40º generates the widest fan and is good for delicate materials and rinsing.
  • > Steam nozzle designed for dispensing high-temperature wet steam.

Tips for Using a Pressure Washer

  • > Consider a cleaning solution, which will make any job easier. If you're concerned about toxicity or hazardous run off, consider a plant-based chemical like Daimer's Eco-Green® line of products.
  • > Let gravity work for you: If you're cleaning a wall or fence, work from top to bottom; for garages or walkways, work downhill.
  • > Beware of fragile objects, like fixtures and glass. A pressure washer can break these items.
  • > Check nozzles for wear if pressure starts to drop. These metal parts are under a lot of force and wear out over time.
  • > Use a clean water supply to prevent dirt particles from clogging the nozzle. Also, consider a nozzle filter.

Related Daimer Links:

Buyer's Guide to Pressure Washers

Pressure washers for car detailing.

Pressure washers with automatic shutoff features.

Pressure washers with a new wet steam technology.

Custom pressure washers.

View over 600 pressure washers and other cleaning equipment.

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