How to Winterize a Pressure Washer | Curb Calc

Water left in the pump can freeze and ruin it. Drain, add pump saver, store above 32°F. Steps for electric and gas models, and where brands differ.

11/6/20264 min read

Curb Calc cover titled How to Winterize a Pressure Washer, with a photo of a man cleaning a car wheel with a pressure washer, a note that freeze damage from water left in the pump isn't covered by Sun Joe's warranty, and a table of flush, drain, engine-run and storage limits from Briggs, Simpson and Sun Joe.Curb Calc cover titled How to Winterize a Pressure Washer, with a photo of a man cleaning a car wheel with a pressure washer, a note that freeze damage from water left in the pump isn't covered by Sun Joe's warranty, and a table of flush, drain, engine-run and storage limits from Briggs, Simpson and Sun Joe.

The last deck rinse of the year is done, and the pressure washer sits in an unheated garage with water still in the pump. Sun Joe's SPX3000 manual says a pump that freezes can be damaged for good, and that freeze damage isn't covered by the warranty. Drain it either way, then add pump saver before the first freeze.

Quick answer: drain the pump, hoses and gun every time (Sun Joe, Briggs), push pump saver through the inlet until it exits the outlet, and store it above 32°F if you can.

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A man crouching to clean a car wheel with a pressure washer wand in front of a brick house
A man crouching to clean a car wheel with a pressure washer wand in front of a brick house

Photo: Anastase Maragos on Unsplash

When to do it

Before the first 32°F night: Sun Joe says store it above 32°F and recommends a pump protector.

Still washing in the cold? Sun Joe says its electric model must not be used below 32°F.

Indoor spot: not next to a furnace; Sun Joe says heat can dry out the pump seals.

Spigots go on the same list: when to turn off outdoor faucets.

High-pressure water spraying a car's spoked wheel
High-pressure water spraying a car's spoked wheel

Photo: Anastase Maragos on Unsplash

Electric pressure washer: 5 steps

From Sun Joe's SPX3000 manual, before winter storage:

1. Disconnect the water.

2. Purge it: run it a few seconds until the leftover water leaves the pump, then switch off and unplug.

3. Empty the rest: every hose and the detergent tanks.

4. Protect the pump: run non-corrosive, non-toxic antifreeze or a pump saver through it.

5. Store it: Sun Joe says a room that doesn't freeze, away from a furnace, with no kinks in the high-pressure hose.

Spring: flush with clear water first; Sun Joe says antifreeze can damage paint.

A pressure washer spray gun and hose lying on wet pavement beside a car wheel
A pressure washer spray gun and hose lying on wet pavement beside a car wheel

Photo: Anastase Maragos on Unsplash

Gas pressure washer: the pump

Briggs & Stratton's how-to says no water should stay in the pump. Its order:

Flush: set the injection tube in a pail of clean water and run on low pressure for 2 minutes. Then turn off the engine and the water.

Release pressure: aim the gun somewhere safe, squeeze the trigger, then set the trigger lock.

Drain: once it cools, disconnect the hoses and drain the hose, gun and nozzle extension. Pull the recoil about 6 times to empty the pump.

Pump saver: on a tarp, with eye protection, push it in through the inlet adapter on about a yard of garden hose. Pull the recoil twice.

Simpson's version: press the can's button until water and Pump Guard come out the high-pressure port.

A wall-mounted hose reel holding a gray pressure hose, with a foam cannon and nozzle tips beside it
A wall-mounted hose reel holding a gray pressure hose, with a foam cannon and nozzle tips beside it

Photo: Anastase Maragos on Unsplash

Gas engine: the brands differ

Run gas engines outdoors, never in a garage.

Briggs & Stratton: add fuel treatment to fresh gas, then run the engine 2 minutes to circulate it.

Simpson, two months or less: fresh fuel and stabilizer, then run 10 minutes with the water on, squeezing the trigger now and then so the water in the pump doesn't overheat.

Simpson, longer than two months: once the engine cools, drain the tank, fuel lines and carburetor, change the oil, and pour half an ounce of new oil into the combustion chamber.

Our read: your engine's manual wins. Mower too? How to winterize a lawn mower.

Storage: clean, dry, out of direct sun (Simpson). Hoses: the best hose reel.

A lone garage with a gray door in a snow-covered field on a foggy day
A lone garage with a gray door in a snow-covered field on a foggy day

Photo: Nellie Adamyan on Unsplash

Pump saver (#ad)

As an Amazon Associate, Curb Calc earns from qualifying purchases.

Briggs & Stratton 6039 Pump Saver, 2 Pack: the pump saver Briggs links from its winterizing how-to. See it on Amazon

A row of garages beside a snowy street on a foggy morning
A row of garages beside a snowy street on a foggy morning

Photo: Adrian Handschu on Unsplash

Pressure washer winter FAQ

Can I leave a pressure washer in a cold garage?

Sun Joe says no for its electric model and won't cover freeze damage. Briggs says pump saver helps prevent freeze damage; store it cool and dry.

Do electric pressure washers need winterizing?

Yes. Sun Joe's manual says to empty the water and use a pump protector.

Can I use RV antifreeze instead of pump saver?

Sun Joe's manual allows non-corrosive, non-toxic antifreeze. Check your manual, and flush it out in spring.

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Sources: Sun Joe SPX3000 manual; Briggs & Stratton, Winterize & Store Your Pressure Washer; Simpson, Winterizing Your Pressure Washer Engine.