How to Clean a Pressure Washer? | Protect Your Investment

To clean a pressure washer, you flush the detergent system, relieve pressure, drain all water, and inspect components like O-rings and nozzles before storing the unit.

A pressure washer left dirty doesn’t just look neglected — it’s a machine begging for costly repairs. Clogged detergent lines, frozen pump seals, and corroded nozzles all trace back to one thing: water left inside. The cleanup process takes ten minutes, but it separates a unit that starts next spring from one that needs a rebuild. The steps below work for both electric and gas-powered models, with one or two variations where they split.

Why Cleaning Your Pressure Washer Matters More Than You Think

Detergent residue attracts dirt and turns gummy inside the pump and chemical intake. Water left in the pump during freezing weather cracks the housing, and that repair usually costs more than a new consumer-grade unit. A thorough clean — the kind that gets the pumps dry — keeps the seals supple, the nozzles clear, and the engine or motor ready for the next job. It also preserves resale value if you ever trade up.

Step 1: Flush the Detergent System

Detergent left in the siphon tube and pump dries into a paste that clogs the chemical intake. Remove the siphon tube from the detergent bottle and place it in a bucket of clean water. Set the spray gun to low pressure and run the machine for 1 to 2 minutes. You will see the water turn clear as all soap residue flushes out.

Flush Without a Low-Pressure Setting

Some budget electric units lack a low-pressure mode. On those, swap to a wider spray tip (40-degree or soap tip) to reduce the effective pressure inside the pump. Run clean water through the same way — the rinse still works fine.

The 5-Minute Drain Routine

Standing water is the pressure washer’s biggest enemy. Without draining, the risk of mold, bacteria growth (yes, they grow inside hoses), and freeze damage rise sharply, especially during seasonal storage.

Step 2: Relieve the Pressure

Turn off the machine and the water supply at the spigot. Point the spray gun away from yourself, your feet, and any pets, then squeeze the trigger until no water sprays out. Engage the trigger lock so nobody accidentally squeezes it while you disconnect things.

Step 3: Power Down and Drain Everything

Electric units: switch the power to OFF and unplug the cord. Gas units: shut off the engine and let it cool for 5 minutes. Disconnect the garden hose, the spray gun, the wand, and the high-pressure hose. Tip the unit to let any pooled water drain out of the hose connections.

For gas models, Briggs & Stratton recommends pulling the recoil starter handle six times to expel water trapped inside the pump. Skip this if you have an electric unit — just tilt it and let gravity do the work.

Step 4: Clean the Chemical Intake and the Exterior

Locate the chemical intake fitting on the pump. Run clean water through it until the water coming out is clear — this prevents dried soap from blocking detergent flow during the next job. Then wash down the entire machine with a damp cloth. Caked-on dirt and grease trap moisture against the engine shroud and paint, accelerating rust on gas-powered units.

Step 5: Inspect the Components That Fail Most Often

Three parts cause 90% of pressure washer leaks and pressure loss: O-rings, nozzles, and hoses.

• O-rings: Pull the high-pressure hose ends and inspect the rubber rings inside the fittings. Cracks or flat spots mean leaks. Replace them for about a dollar.
• Nozzle: Poke a paper clip into the nozzle opening to clear any grit. Lock it into the wand and make sure it seats firmly.
• Hoses: Run your fingers along the high-pressure hose and feel for cuts, bulges, or soft spots. A failed hose under 2,000 PSI is dangerous. Replace immediately if damaged. New hoses must exceed your machine’s maximum PSI rating.
• Screens: Inspect the water inlet screen and any inline screen. If clogged, rinse it under the faucet; if torn, replace it.

Pressure Washer Maintenance Schedules at a Glance

Common Mistakes That Kill a Pressure Washer

Every experienced repair tech lists the same death blows. A Lowe’s pressure-washer maintenance guide covers the basics well, but the patterns repeat everywhere.

• Running with the nozzle closed: Pressure builds inside the hose with no exit, stressing the pump seals and hose walls.
• Running without water connected: The pump relies on flowing water for cooling. Dry running destroys the seals in seconds.
• Storing with old gas: Gasoline left from the previous season gums up the carburetor. Add fuel stabilizer or drain the tank before storage.
• Skipping the detergent flush: Dried soap forms hard deposits inside the pump that resist cleaning.
• Storing while wet: Insects and moisture inside the pump lead to mold growth and internal rust.

Ready to Clean or Ready to Buy?

If your current pressure washer is past saving — cracked pump, seized engine, or corroded beyond practical repair — you can skip the salvage work and look at a direct replacement. For homeowners who want a machine that starts on the first pull and handles driveways, decks, and siding without constant maintenance, the tested recommendations at our roundup of the best pressure cleaners for home use cover electric and gas models that balance power with winter-ready durability.

Winter Storage Checklist

If you are putting the pressure washer away for the season, run through the steps above, then add these:

• Add fuel stabilizer to a full gas tank, run for 2 minutes to circulate it, then top off with fresh gas.
• Store in a well-ventilated area out of direct sun and rain. Keep it off the concrete floor — a sheet of plywood or a shelf works.
• Make sure children cannot reach the unit or the chemicals stored nearby.
• If you live in deep-freeze territory, tilt the machine forward until every drip of water stops. A teaspoon of ice in the pump housing is all it takes to crack it.

One clean, dry, drained pressure washer starts every time. The ten-minute post-use routine pays for itself on the first spring job you don’t have to skip.