Can You Run Dawn Dish Soap Through a Pressure Washer?

You’re standing in your garage. Pressure washer at the ready. Eyeing that bottle of Dawn dish soap under your kitchen sink. It cuts through tough grease on dishes like a champ. So why not throw some in your pressure washer and supercharge your cleaning game, right?

Hold up.

The internet is full of people swearing by Dawn in their pressure washers. “Works great!” they say. “No problems!” they claim. And then there’s the other half telling you you’re about to destroy your $300 machine and void every warranty known to mankind.

So who’s right? 

Today, we’re settling this once and for all. We’ll break down what happens when you use dish soap in a pressure washer and hose. Why some people get away with it (and others don’t), and what you should be using instead if you want your machine to last longer than your last New Year’s gym membership. Let’s get into it!

Pros of Using Dawn Dish Soap in Your Pressure Washer

Okay, so why do so many people reach for that blue bottle when it’s pressure washing time? Let’s be real; there are actually some legit reasons why Dawn has become the unofficial mascot of DIY pressure washing. Here’s what makes it tempting:

It’s Ridiculously Cheap and Available

Let’s start with the obvious one. Dawn costs way less than specialized pressure washer detergents, and you probably already have a bottle sitting under your kitchen sink right now. No need to make a special trip to the hardware store or order some fancy cleaner online that won’t arrive until next Tuesday.

For quick jobs where you don’t want to spend $20 on a gallon of specialized detergent, Dawn is the convenient option. We get it. Convenience wins sometimes.

The Grease-Cutting Power is Real

Dawn is famous for its ability to cut through grease and oily residues. The same power can be fairly well translated into the oil splashes on your driveway or the grimy accumulation on your deck.

Have hard-to-remove grease on your garage floor? Engine oil on your concrete? Dawn can help break that stuff down. It is made to address grease on a molecular level, and that capability does not evaporate simply because you put it in a pressure washer and not on a sponge.

It’s Surprisingly Eco-Friendly

In case you are concerned about what is flowing into your garden or the storm drain, Dawn gets some points here. It is biodegradable and is usually assumed to be less harmful to plants and animals than the more toxic cleaners.

It’s Gentle on Most Surfaces

Dawn’s formula is relatively gentle, and therefore, you have fewer chances to ruin painted surfaces, remove protective layers, or scratch sensitive materials. See how that compares with some industrial-strength pressure washer detergents, which might likely remove the paint off a car unless you take particular care.

Cons of Using Dawn Dish Soap in Your Pressure Washer

Alright, reality check time. We just laid out all the reasons why people love using Dawn in their pressure washers. Now let’s talk about why your pressure washer manufacturer is probably sweating bullets at the thought of you pouring that blue bottle into their machine.

The Foam Situation is Out of Control

Remember how we said Dawn is great at cutting grease? Well, it’s also really great at making foam. Like, mountains of it. Dish soaps produce too much lather, and that lather may cause undue stress on your pressure washer and may render the pump ineffective or even broken.

Say Goodbye to Your Warranty

Oh man, this one hurts. Pull out your pressure washer manual right now. Go ahead, we’ll wait. See that section about approved detergents? Manufacturers warn against using household soaps in their pressure washers, and if damage occurs, your warranty may not cover repairs.

That $300 repair? That’s on you now. Hope those savings on detergent were worth it!

The Residue Problem Nobody Talks About

Dish soaps are known to leave behind a thin layer on the surface they are applied on, and this layer may be favorable to dirt. You wash your deck and/or siding, and then you are so proud of yourself, but two weeks later, it gets dirty once again. Faster than it did before.

Why? Because that invisible Dawn residue is sitting there like a dirt magnet. You just created more work for yourself. Congratulations!.

It Doesn’t Play Well with Other Chemicals

Most dish soaps are not chlorine resistant, as opposed to laundry detergents or surfactants that are specifically made to be used in pressure washing.

What does that mean? In case you are combining Dawn and bleach (some people do so to remove mold), it will neutralize the power of bleach. It gets highly liquid, smells no more, and cannot clean well.

Oh, and Dawn’s label specifically says not to mix it with bleach. But who reads labels, right? (You should. You really should.)

The Step-by-Step Guide on How to Use Dawn in Your Pressure Washer

In case you choose to use Dawn anyway, you might as well do it correctly in order to minimize the risk of your pressure washer and hose becoming a costly lawn ornament. All you need to do is to follow the steps below!

Step 1: Check Your Pressure Washer Manual (Seriously, Do This)

We know, we know. Reading manuals is about as exciting as watching paint dry. But trust us on this one. If your manual explicitly says “don’t use dish soap,” maybe don’t use dish soap. Or at least know you’re voiding your warranty before you start. Your call.

Step 2: Get Your Dilution Ratio Right (This is Critical)

This is where most people make mistakes. They just pour Dawn straight into the detergent tank and wonder why their driveway looks like a foam party gone wrong.

Here’s the math made simple:

• Light cleaning: 1-2 ounces Dawn per gallon of water (roughly 2-4 tablespoons)
• Medium cleaning: 3 ounces Dawn per gallon of water (about 1/3 cup)
• Heavy-duty cleaning: You probably shouldn’t be using Dawn for this

Mix it in a bucket first. Stir the mixture until the soap is fully dissolved. Then, pour it into the detergent tank. 

Step 3: Apply, Rinse and Wash 

Spray the detergent and let it sit on the surface over a period of 5-10 minutes without letting it dry out. Next, use your high-pressure nozzle and spray down the surface, making sure not to leave any soap behind.

Final Words

Dawn is that friend who is fun to hang around with once in a while, but would certainly get on your nerves should you allow them to permanently stay in your guest room. When you need a one-off cleaning job in a hurry? Sure, it’ll probably work fine. Using it as your new pressure washing detergent? That is what you are left with: a dead pump and an invalidated warranty.