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.

Custom pressure washers.

Shopper Approved Banner
Why Choose Daimer

Years in Business

World's largest supplier of commercial and industrial steam cleaners.

Questions? Ask Us
Our Distinguished Clients
How a Pressure Washer Works

How a Pressure Washer Works