How Does a Pressure Washer Work?

How Does a Pressure Washer Work? Understanding Its Mechanics and Uses

From blasting away stubborn grime to clearing blocked drains with surgical precision, pressure washers have become essential tools across homes, trades, and industries. Whether you’re scrubbing the patio with a narrow nozzle, detailing a vehicle, or breaking through tree roots deep in a drainpipe, pressure washers get the job done fast, clean, and efficiently.

But how do these high-powered machines actually work? Here’s a quick summary of the different types and how to choose the right one for your needs?

Let’s break it all down and help you get the most from your pressure washer or jetter – whether you’re a weekend warrior or a full-time tradie.

What is a Pressure Washer?

At its core, a pressure washer—also known as a power washer—is a high-pressure mechanical sprayer that works in conjunction with a water pump designed to remove dirt, grease, mould, paint and debris from a wide variety of surfaces.

It transforms clean water from your main water supply, usually through a standard garden hose, into pressurised water delivered at high velocity by an electric motor. This cleaning process is far more effective than using an ordinary low-pressure hosepipe, especially when dealing with ingrained grime or large surface areas.

Pressure washers are used in residential, commercial and industrial settings to clean everything from cars and concrete to drains and machinery. The best part? They use quite a lot less water than traditional cleaning methods by focusing that flow into a high-powered stream.

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How Does A Pressure Washer Work?

A pressure washer works by using a motor to power a pump, which in turn increases the pressure of water coming from your water supply. The pump accelerates the water flow, transforming ordinary cold water from your tap into a concentrated, high-pressure stream that powers through dirt and grime.

Here’s how the process typically goes:

1. Water enters the washer from a tap via a hose.
2. The pump squirts this water at high pressure through a high-pressure exit hose.
3. The trigger gun controls when and how pressurised water is released.
4. A variety of nozzles and attachments help users customise spray to suit the job at hand.

Some models mix in detergent flows, allowing for soapy water application. This is especially useful for cleaning grease, oil, or delicate surfaces where chemical action is needed. The water exits the nozzle in high-energy water jets pressurised to as much as 5000 PSI (pounds per square inch), making light work of stubborn messes.

The entire process is designed to clean efficiently – breaking down dirt and other contaminants at the molecular level and saving time and effort.

Key Components of a Pressure Washer

At the heart of every pressure washer is a water pump, typically powered by an electric motor, though some commercial or heavy-duty models may use a diesel engine or petrol motor. When clean water flows in through the water inlet – usually connected via a garden hose to your main water supply – the pump kicks in to increase the pressure.

This transformed stream of pressurised water is then forced out through a high-pressure exit hose, delivering powerful water jets pressurised to hundreds or even thousands of pounds per square inch. This high-speed water stream is what makes pressure washers so effective at cutting through dirt, grease, and even old paint. In many models, there’s also a detergent flow system that mixes soapy water into the stream for deeper cleaning, particularly useful on engines, driveways, and greasy surfaces.

Safety Features & Water Flow

The trigger gun controls the flow. It connects to a variety of nozzles and attachments that help customise the spray pattern depending on the task—whether you’re cleaning timber decks, blasting concrete, or unclogging drains.

Most washers come equipped with essential safety features like a ground-fault circuit breaker (GFCB) or residual current device (RCD), which help to protect against electrical faults when operating around water sources. With only one hose delivering such powerful cleaning action, it’s critical that all components—from the pump to the nozzle—are regularly maintained for safe, optimal performance.

Pressure Washer Types: Hot or Cold Water?

There are two main types of pressure washers, each suited for different cleaning needs:

Cold Water Pressure Washers

Cold water pressure cleaners are the most common units used by homeowners and tradespeople alike. Cold water flows through the system and blasts away dirt, dust, and mud.

These washers are perfect for:

• Cleaning driveways, patios, and footpaths
• Washing cars, boats, and outdoor furniture
• Stripping away loose paint or mud

Cold water pressure washers are generally lighter, more affordable, and easy to maintain. You can also mix in as much detergent as needed to improve cleaning performance.

Since they don’t apply heat, they’re also better for materials like wood, plastic or composite decking that might warp under high temperatures.

Hot Water Pressure Washers

If you’re dealing with oil, grease, or industrial grime, a hot water pressure washer is the way to go. These units use a burner system that heats the water before it’s repressurised, containing heat, pressure, and soapy water to lift even the toughest contaminants.

These machines are typically powered by a diesel engine or petrol motor, making them ideal for construction sites, workshops, and industrial cleaning applications.

Jetters: For Drain Cleaning and Serious Blockages

Pressure washers are great for surface cleaning, but if you’re a plumber or in drain maintenance, you need something more powerful—like a high-pressure water jet.

Drain jetting, also known as sewer jetting, uses a flexible high-pressure exit hose and specialist cleaning attachment jetting nozzles to direct pressure through plumbing systems. The force of the water jets repressurised through the pipe not only clears blockages but also cleans pipe walls, preventing future issues.

Jetters are especially effective for:

• Breaking up tree roots
• Cutting through grease and soap buildup
• Clearing recurring drain blockages
• Navigating complex piping with bends and elbows

The King Cobra Series

Our King Cobra Cube jetter delivers serious power—5,000 PSI, to be exact. It combines a heavy-duty pump with rotating and vibrating nozzle tech that smashes through stubborn blockages deep in the drain. Pair it with a Mustang nozzle, and you’ll have one of the most effective drain-cleaning tools on the market.

Other popular jetters include:

• KegJet 25 – Compact and powerful for mobile plumbing jobs.
• RamJet 5000 – Big pressure for big jobs.
• Python Trailerjet 25 – A fully-featured trailer unit powered by a Honda IGX800 fuel-injected engine.

If you’re dealing with drains that are constantly blocking up or the same issue keeps reoccurring, drain jetting could be the most effective solution. Whether it’s a persistent plumbing problem or a deeper issue within your external sewer lines, investing in a sewer jetter can help you clear those stubborn blockages once and for all.

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Choosing the Right Pressure Washer or Jetter

When selecting a unit, there are a few key questions to ask:

• What kind of jobs are you tackling? Light cleaning or industrial muck?
• Do you need hot or cold water cleaning?
• Will you be adding detergent flows into the mix?
• What power source do you have access to—electric, petrol, or diesel engine powered?
• How portable does it need to be? Do you need a trailer-mounted unit or just a compact machine?

Whether you need a basic cold water cleaner or a top-tier jetter, Melbourne Jetter Centre stocks the full range—high-pressure washers, jetters, spare parts, accessories, and more.

Need help? Give us a ring at (03) 9792 2350.

Residential vs Commercial Use

Residential:

• Great for general cleaning
• Usually electric-powered
• Ideal for cars, patios, siding, outdoor furniture
• Less pressure (1500–3000 PSI)

Commercial:

• Higher PSI and water flow for deep cleaning
• Often powered by diesel engines
• Capable of handling oil, grease, industrial grime, and drain jetting
• Built for daily use and rough conditions

Pressure Washing Techniques

A few smart tips and techniques can go a long way in achieving better results:

• Use a wide fan nozzle for general cleaning and a narrow jet for tough spots.
• Keep the nozzle about 30cm from the surface.
• Work from the top down to avoid streaking.
• Move slowly to let the pressurised water do the work.
• Always rinse after applying soapy water or detergents.
• Use the correct attachments – turbo nozzles, foamers, and sandblasters each serve a purpose.

Safety First: Important Precautions

Pressure washers can cause serious injury or property damage if misused. Always keep these tips in mind, and consider doing some training if you are using it professionally:

• Always wear gloves and eye protection.
• Make sure the area is clear of obstacles, people, and pets.
• Use on flat, stable ground to avoid losing control.
• Check hoses and fittings regularly for wear and tear.
• Never point the spray at yourself or anyone else.
• Ensure your one-hose system isn’t leaking or blocked.

Want to learn more about safe use and best practices for using a water jetter? You can read our Pressure Washer Safety Guide here.

Maintenance and Care

Keeping your machine in top shape means consistent performance and longer lifespan:

• Flush the system after each use.
• Clean filters and check for clogs in the water inlet.
• Lubricate the pump as per manufacturer instructions.
• Inspect seals, high-pressure hoses, and nozzles regularly.
• Store the unit in a dry, protected space to prevent weather damage.

Need repairs or a tune-up? Melbourne Jetter Centre offers authorised pressure washer and jetter repairs and carries parts for all major brands.

When Your Pressure Washer Won’t Work – Troubleshooting Tips

If you are having issues with your pressure washer, you can usually solve them by doing some basic troubleshooting.

Here are some common issues and how to fix them:

Not Enough Pressure?

• Check for blockages in the nozzle or hose.
• Make sure your garden hose is delivering enough flow from the tap.
• Inspect the pump for wear or damage.

Leaking Water?

• Tighten all connections.
• Check O-rings and seals for deterioration.
• Make sure the water inlet filter isn’t clogged.

Unit Won’t Start?

• For electric models, check the power source and any tripped breakers.
• For fuel units, check oil levels, fuel, and spark plugs.

If you’ve tried all the standard troubleshooting recommended by your manufacturer and are still having problems, get in touch with our team to book it in for a service or repair.

Accessories and Add-ons

Upgrade your cleaning power with quality accessories:

• Turbo Nozzles: Create a rotating spray for deep cleaning.
• Foam Cannons: Apply thick, soapy water to cars, boats, and siding.
• Sandblasting Kits: Strip rust and paint down to the base metal.
• Hose Reels: Keep hoses tidy and protected from wear.
• Spare Parts: Always handy to have on hand—especially for seals, filters, and nozzles.

Training & Certification

Using a jetter professionally? Safety and efficiency are key. Trainright Industrial Services offers nationally recognised courses in:

• High-pressure water jetting
• Drain cleaning
• Vacuum

Courses are available for beginners and pros alike, helping you operate equipment safely, reduce risk, and improve job quality. Download their brochure and get started today.

Final Thoughts

A pressure washer is more than just a cleaning tool—it’s a time-saving, grime-busting, problem-solving machine. Whether you’re cleaning the driveway at home or jetting sewer lines on a worksite, understanding how it works and choosing the right setup can make all the difference.

Need help picking the right gear? Call the team at Melbourne Jetter Centre or explore our full range online.