How to Winterize Your Pressure Washer: Freeze-Proof Storage Guide

I Learned the Hard Way

It was January in Ohio. Thermometer read 12°F. I went to grab my pressure washer from the shed to beat some ice off the back steps. The trigger felt stiff. I squeezed anyway. Nothing came out but a trickle. Then I saw the crack—a split running three inches down the pump housing. Ice had expanded inside the pump, blowing it apart like a soda can in a freezer. That repair cost me $180. A new pump was $150. The bottle of RV antifreeze sitting on my shelf? $4.

Don't be me. Winterizing a pressure washer takes 20 minutes. Skipping it costs you the machine.

Why Winter Kills Pressure Washers

Water expands by about 9% when it freezes. Your pump is full of tight clearances—pistons, valves, seals. Ice doesn't compress. It shatters brass, cracks aluminum, blows out rubber seals. Even a hairline crack in the pump head means the unit is junk.

The pump isn't the only victim. The hose, the wand, the spray gun—anywhere water sits will split. I've seen trigger handles snap in half. I've had a hose burst like a party balloon in spring.

And here's the killer: most damage happens invisibly. You won't know until you try to start it next April, and by then the warranty is long gone.

When to Winterize

Don't wait for a hard freeze. Do it before the first night where temps dip below 32°F. In most northern states, that's mid-October through early November. In the South, you might have until December.

I aim for the last weekend of October. It's a hard deadline I put on my calendar. If you wait until the morning after a freeze, you've already lost.

One trick: check your local forecast for the first "frost warning." Do it that weekend. Not the next weekend. That weekend.

The Right Stuff to Use

There's a product made for this: pump saver, also called pump winterizer. It's a silicone-based lubricant that coats the internal seals and prevents corrosion. A 4-ounce bottle runs about $8–$10 and treats one machine. I use the Stuff brand. It works.

But the real MVP is RV antifreeze. Not automotive antifreeze. Not the green stuff. You need the pink, non-toxic RV antifreeze designed for drinking water systems. A gallon costs $4–$6 at Walmart. Automotive antifreeze is poison and eats pump seals.

Do not use windshield washer fluid. It's methanol-based and doesn't protect below about -20°F. It also dries out rubber. I tried it once. Seals were shot by spring.

Step-by-Step: How I Do It in 20 Minutes

Here's the exact process I follow. No shortcuts.

Step 1: Flush the system with clean water. Run your pressure washer with a garden hose attached for about 30 seconds. This pushes out any dirt, old soap, or sediment sitting in the pump. Shut off the engine (or unplug the electric unit).

Step 2: Disconnect the water supply. Unscrew the garden hose from the pressure washer inlet. Let any water drain from the hose. Coil it up and store it inside your garage or basement. Hoses left outside crack even if they look "empty."

Step 3: Run the engine dry. Pull the starter cord (or turn on the electric motor) for about 5 seconds without water connected. This expels leftover water from the pump. You'll hear the engine sputter. Don't run it longer than 10 seconds—you can damage pump seals running dry too long.

Step 4: Mix your brew. I use a 5-gallon bucket. Fill it with 2 gallons of water. Add the entire bottle of pump saver. Then add 1 gallon of pink RV antifreeze. Stir with a stick. This gives you a protective solution that won't freeze down to about -50°F.

Step 5: Put the suction hose into the bucket. Most pressure washers have a chemical injection hose—the clear tube with a filter on the end. Stick that into the bucket. If your unit doesn't have one, you can buy a siphon kit for $10. Direct the spray gun into the bucket.

Step 6: Run the mix through. Start the engine. Squeeze the trigger. Let the machine draw the solution from the bucket. You'll see the pink liquid come out of the nozzle. Keep running until the bucket is empty. Release the trigger. Shut off the engine.

Step 7: Drain and store. Remove the suction hose from the bucket. Pull the starter cord a couple more times to clear any remaining liquid from the pump. Disconnect the spray gun and wand. Store the pressure washer indoors—garage, basement, shed. Don't leave it outside under a tarp. I've done that. The tarp traps moisture, and you get rust.

That's it. Whole thing takes me 20 minutes, including cleanup.

What About Gas Engines?

The engine itself needs love too. Here's what I do:

• Stabilize the fuel. Gasoline degrades in 30 days. If it sits all winter, it turns to varnish and clogs the carburetor. I add Sta-Bil fuel stabilizer to the tank before my last use. Run the engine for 5 minutes to work it through the system.
• Change the oil. Old oil contains acids and moisture. I change it in fall so the engine sits all winter with fresh oil. Takes 10 minutes. Use 10W-30 for most Honda and Subaru engines.
• Spray fogging oil into the cylinder. Remove the spark plug. Spray a 2-second burst of fogging oil into the cylinder. Pull the starter cord a couple times to coat the cylinder walls. Reinstall the spark plug. This prevents rust from forming on the cylinder walls over winter.
• Remove the spark plug and dip it. I keep the removed plug in a baggie with a few drops of oil on the electrode. Replace it in spring.

I lost a Honda GX200 engine to a seized cylinder because I skipped the fogging oil step one year. That was a $400 mistake.

Electric Pressure Washers Are Not Off the Hook

I know a guy with a $200 electric Karcher. He said "it's plastic, it'll be fine." Come spring, the pump was cracked and the wand had split. Electric units have the same problem—water freezes, pump breaks.

For electric units, the process is simpler. You still need to run RV antifreeze through. But you skip the engine steps. Drain the water. Run pink stuff through. Done.

One thing electric owners miss: unplug the unit and store the cord dry. Don't wrap it tight. Coil it loosely. Tight coils break the insulation over winter.

Storing the Hose and Accessories

The hose is the second most common failure point, after the pump. Don't leave it coiled on the ground outside. Water sits in the low points and freezes.

Here's what I do:

• Drain the hose completely by holding one end up and letting gravity drain it.
• Coil it in a figure-8 pattern (prevents kinks).
• Store it in a plastic tote in the garage. Not on a concrete floor—moisture seeps up and rots the rubber.
• Spray the foam grip on the wand with WD-40. Prevents moisture from freezing the trigger mechanism.

I lost a $50 spray gun because I left it in the bed of my truck overnight. The trigger was frozen solid in the morning. Took a hair dryer to thaw it, but the seals were already stretched.

What Happens If You Skip It?

Let me paint you a picture. It's March. You pull out the pressure washer. Hook up the hose. Turn on the water. Pull the starter cord. Nothing. Or maybe a loud bang. Or water leaking from the pump housing.

Best case: you need a new pump. $100–$250. You can replace most pumps with a bolt-in kit from Amazon. It's doable with basic wrenches. About an hour of work. Worst case: the frame is cracked, the engine is seized, and the entire unit is scrap. You're buying a new pressure washer.

Average cost of a gas pressure washer: $400–$800. Cost of winterizing: $15 for pump saver and antifreeze. That's a 50x return on investment.

And the time? I spent 2 hours swapping a pump once. That's $120 of my time at my hourly rate. Winterizing takes 20 minutes. Math works out.

Frequently Asked Questions

Can I just drain the water and skip the antifreeze?

No. Water hides. It's in the pump cavities, in the unloader valve, in the chemical injector. You cannot gravity-drain a pump completely. There's always a tablespoon of water left that will freeze and crack something. Trust me, I tried. Pump cracked anyway.

Do I need to remove the hose from the machine?

Yes. Always. The hose traps water at the connection point. If you leave it attached, the water will freeze and seize the brass fitting. You'll need heat to get it off in spring. Separate everything.

Can I use windshield washer fluid instead of RV antifreeze?

No. It's methanol. It freezes at higher temps than you think. It also eats rubber seals. I ruined a pump with it. Spend the $4 on pink RV antifreeze.

How long does the winterizing protection last?

A whole winter. The silicone-based pump saver doesn't evaporate. The RV antifreeze stays liquid down to -50°F. You're set until spring. Just don't start the engine until you're ready to use it.

My pressure washer has an oil drain. Do I really need to change it?

Yes, if you want the engine to last past 5 years. Old oil sitting all winter forms sludge. Fresh oil protects the internal bearings. I skip it on cheap units I plan to replace, but on a Honda or Subaru engine, it's worth the 10 minutes.

What if I already forgot and it froze overnight?

Don't try to start it. Thaw the entire unit in a heated space for 24 hours. Then disassemble the pump and inspect for cracks. If you see white powder around fittings, that's aluminum corrosion from freeze damage. The pump is likely toast. Run water through before you attempt to start. If it leaks, replace the pump.

Should I store the pressure washer vertical or horizontal?

Vertical, with the pump at the lowest point. This lets any residual water run to the pump and collect, rather than pooling in the engine. I store mine upright on a dolly. Keeps it off the concrete too.

That's it. Twenty minutes, fifteen bucks, and you're set. Your pressure washer will fire up first pull next spring, and you won't be staring at a cracked pump cursing the day you bought it. Do the work now. Thank me in April.