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

Why You Should Care (Before You Cry Over a $400 Paperweight)

Last November, I got lazy. I’d just finished pressure washing my fence, the temperature was dropping, and I figured, “It’ll be fine for one more week.” That week turned into two. Then we got a hard freeze. When I went to fire up the washer in March, I turned the key, pulled the cord, and heard a sound like a coffee can full of gravel. The pump was cracked. The unloader valve was seized. The repair cost me $220 — nearly half the price of a new unit.

I’ve made that mistake three times in twenty years. I’ve also watched a neighbor leave his pressure washer out all winter, then act surprised when the pump housing split like a dropped egg. Don’t be that guy. Winterizing a pressure washer takes about 30 minutes and saves you a world of hurt.

Perfect Timing: Don’t Wait for the First Freeze

I winterize mine the first weekend after the last big leaf drop, usually mid-to-late October where I live (Zone 6). But the real rule is simple: do it before the first overnight freeze hits below 28°F. Water expands by about 9% when it freezes. That expansion is strong enough to crack cast-iron pump heads, split brass fittings, and destroy internal seals.

Check your 10-day forecast. If you see a “frost advisory” or temps dropping below 32°F at night, that’s your deadline. Don’t wait for the “big freeze” — one bad night is all it takes.

Gear You’ll Need

You don’t need much. Here’s what I grab from my garage:

• Pump saver / antifreeze (RV-type only): I use Pump Guard or Briggs & Stratton PumpSaver (about $8 for a 12-oz bottle). No, cheap windshield washer fluid doesn’t work — it lacks the lubricants and can corrode seals.
• A short length of garden hose (3-4 feet) with a male-to-male adapter or a siphon kit. Most hardware stores sell a $6 winterizing kit.
• A bucket with 2-3 quarts of warm water.
• WD-40 or silicone spray for the hose fittings and nozzle.
• A microfiber cloth (or an old t-shirt).

Step-by-Step: The 30-Minute Method

Step 1: Run the machine dry

Shut off the water supply. Disconnect the garden hose from the pressure washer. Then start the engine (or turn on the electric motor) and squeeze the trigger on the gun. Let it run until no more water comes out of the wand — about 30-45 seconds. This clears the vast majority of free water from the pump, hose, and spray gun. If you skip this, you’re just diluting the antifreeze and leaving pockets of plain water inside.

Step 2: Mix the pump saver

Pour the pump saver into a bucket with 1-2 quarts of warm water. Follow the bottle instructions — most 12-oz bottles treat 2-3 gallons of solution. I usually mix a little stronger, say 6 oz per quart of water, because I’m paranoid.

Step 3: Siphon the mix through the pump

Attach your short hose to the water inlet on the pressure washer. Put the other end into the bucket of pump saver mixture. Make sure the water outlet (the high-pressure side) goes into a second bucket or drain — don’t spray it on your lawn. Start the engine and pull the trigger. The pump will draw the mix in and push it out. Let it run until you see the pink or blue solution coming steadily from the wand. That means the pump, hose, and gun are all filled with antifreeze.

Step 4: Coat the seals (forget this and regret it)

Disconnect the spray gun and wand from the high-pressure hose. Squirt a little pump saver directly into the hose ends. Then spray a 1-second burst of WD-40 into the gun’s trigger assembly and the nozzle’s connection. This prevents O-rings from drying out and cracking over winter. I lost a $40 spray gun one year because the internal seal got brittle and leaked — all because I didn’t spray it.

Step 5: Drain the fuel system (gas-powered only)

If you have a gas washer, stale fuel is your second-biggest enemy. I add Sta-Bil fuel stabilizer (about $5) to the gas tank, run the engine for 2 minutes to circulate it, then either shut off the fuel valve and run it until it dies, or drain the carburetor bowl. If you leave untreated gas in the carb, the ethanol absorbs moisture and gums up the jets. I rebuilt my carburetor last spring — a simple job that still cost me $15 in gaskets and 45 minutes of my afternoon.

What Happens If You Skip It (The Hard Truth)

I’ve seen three outcomes, all bad:

• The Cracked Pump: Water freezes, expands, and splits the pump housing. You’ll see a hairline crack near the water inlet or around the unloader valve. Replacement pump for a mid-range gas washer? $80-$150. Plus an hour of labor.
• The Seized Pump: Water doesn’t freeze solid, but the pump components rust together. You’ll try to start it in spring and the engine will bog down or stall. You might hear a grinding sound. A seized pump is usually a write-off.
• The Gunked-Up Gun: The spray gun’s internal check valve or ball bearing gets locked up from corrosion. You pull the trigger and nothing happens — or it drips constantly. A new spray gun with wand is $25-$60.

I’ve personally experienced two out of three. The seized pump taught me a $180 lesson. Don’t be like past-me.

Where to Store It

Inside a heated space is ideal — basement, garage that stays above 32°F, or a shed with a heat lamp. But I know not everyone has that. If you must store it outside, get a heavy-duty pressure washer cover ($20 on Amazon). Prop it so it’s off the ground (pallets or bricks work). And tilt the machine so the water drain plug (usually at the back of the pump) is the lowest point. That way any condensation drains out instead of pooling.

Frequently Asked Questions

Can I just blow it out with compressed air instead of using antifreeze?

Short answer: No. Compressed air can blast residual water deeper into the pump’s internal passages and seals, where it can still freeze. You’ll think you’re dry, but a trapped droplet will crack a check valve. I learned this from a mechanic buddy after I blew out a machine and it still failed. Use the liquid method.

How much pump saver do I really need?

One $8 bottle covers one machine for two seasons if you mix it right. You’re not filling the entire system with pure undiluted goo — you’re circulating a 10-20% solution through the internals. Overkill doesn’t hurt, but a single 12-oz bottle mixed per the instructions is enough for a standard 3,000-3,500 PSI washer.

My electric pressure washer is small. Do I need to do all this?

Yes. Electric pumps are usually made of aluminum or plastic — even more prone to cracking. The steps are exactly the same, but you just run the motor for the siphon step. Electric pressure washers often have plastic unloader valves that snap like Twizzlers in a freeze.

What about the high-pressure hose?

Hoses are usually rubber and can handle freezing better than pumps. But if you leave water trapped in the hose and it freezes, the hose can kink permanently or split at the fittings. I just tilt the hose and let gravity drain it after Step 1. Never had a problem.

Do I need to remove the spray nozzle for storage?

I do. I pop off the last nozzle adapter, spray a little WD-40 in the threads, and store it in a ziplock bag taped to the pressure washer handle. That way I don’t lose it, and it doesn’t corrode into the gun. Plus, if I forget, the nozzle is the cheapest part to replace — but why even risk it?

That’s it. Thirty minutes, maybe 40 if you’re slow like me. Do it on a Saturday afternoon, sip a coffee, and feel smug while your neighbors are Googling “how to replace pressure washer pump” in March. I’ll be pulling mine out of the garage, giving it a little squirt of start-up spray, and washing winter grime off the patio by the first sunny weekend. You should be able to do the same.