What Is Muriatic Acid and Is It Safe For Home Cleaning?

By: Allison Troutner  | 
scrubbing tile floor
When your home cleaning job is too tough for ordinary cleaning products, perhaps muriatic acid is the product to try. Oranje Travel/Shutterstock
Key Takeaways
  • Muriatic acid is a highly corrosive cleaner that effectively removes mold, stains, and rust from surfaces like brick, concrete and stone.
  • It requires careful handling with safety gear, including goggles, a respirator, gloves and full-coverage clothing to prevent skin burns.
  • Always dilute muriatic acid with water before use (typically one part acid to 10 parts water), apply the solution carefully, let it sit, then rinse off and neutralize with an ammonia solution if necessary.

As every homeowner knows, there are cleaning jobs and then there are tough cleaning jobs. You can usually tackle the former with products you have around the house like baking soda, vinegar or even the favorite Magic Eraser.

But none of those will make a dent in rust on stainless steel or mold on concrete walls in your basement. What cleaning product do you use then? That's where muriatic acid can be helpful. It's one of the strongest cleaners you can buy. But you can't just use muriatic acid anywhere — it is an acid after all.



What Is Muriatic Acid?

The name muriatic acid is derived from the Latin word muriaticus, which means "pickled in brine" because it's used as a pickling agent to remove oxides from the surface of metals. It's a type of acid, as the name implies — hydrochloric acid (HCl) to be specific.

Hydrochloric acid is a purer and more toxic form of muriatic acid. Hydrochloric acid has a normal pH of 1.5 to 3.5, while muriatic acid has a pH of about 1 to 2. Muriatic acid is also less potent because it's diluted with water (usually around 31.5 percent HCl) and contains impurities like iron. The impurities give muriatic acid a yellowish color and distinct smell, compared to clear and odorless hydrochloric acid.


Arab scholar Jabir ibn Hayyan — considered a "father of alchemy" — is credited with discovering hydrochloric acid via experimental alchemy in the eighth century by distilling sulfuric acid with hydrochloric acid and nitric acid. Scholars also credit him with the invention of several early chemical processes including crystallization, calcinations, sublimation and evaporation.

Today you can pick up muriatic acid at most home improvement stores for less than $20 a gallon. It's not as hazardous as pure HCl, and you can use it safely if you take precautions.

hydrochloric acid
Muriatic acid is just a diluted version of hydrochloric acid.


How to Use Muriatic Acid

The first thing you need to do when using muriatic acid is wear safety gear. That should include goggles, a respirator, gloves and full-coverage clothing, as exposed skin could be burned if it comes in contact with the acid.

Once you have on the proper safety gear, you're good to go. Muriatic acid is corrosive but that is what makes it really good at getting rid of mold, stains and rust from a variety of surfaces, including brick, concrete and stone, and swimming pools.


Despite that muriatic acid is made for cleaning, you still need to dilute it with water before you use it. How much you weaken it will depend on what job you're tackling, but according to BobVila.com, a good formula is one-part muriatic acid to 10 parts water.

When diluting it, pour the acid into the water, not the other way around. And never ever mix muriatic acid with other cleaning products.

Carefully apply that solution to any mold or hard surface and let it sit for about 10 minutes, then rinse it thoroughly with water. BobVila.com says you can spray the area afterward with a solution of one-part ammonia to 10 parts water to neutralize any remaining acid. Then simply leave the area to dry completely.

Muriatic acid is also used to help balance pH in pool water. If the pH is too high, muriatic acid can help bring parity to your pool. But be sure to buy a swimming pool cleaner in this case. It's no different from other muriatic acid products, but it will have thorough instructions on how to use it safely in your pool. No fun going for a dip and coming out with chemical burns.

pool test kit
If your pool's pH level is off, you can use muriatic acid to get the pH balance back to the proper level.
Bill Oxford/Getty Images


Take the Skull and Crossbones Seriously

Muriatic acid is easy to get your rubber glove-covered hands on. As we mentioned, you can purchase it at most major home improvement stores. But don't get complacent and ignore the hazard symbol on the container. The stuff is poisonous, caustic and can cause serious health issues without proper protective measures.

Ideally, use muriatic acid as a last cleaning resort. Instead, try a less toxic cleaning product first. Direct contact with muriatic acid causes chemical burns on the skin, severe irritation to the eyes and throat, and can even cause blindness if it comes in contact with your eyes, according to the Centers for Disease Control and Prevention.


Use muriatic acid only in highly ventilated spaces and take care to dispose of it properly to reduce the chances of it contaminating local ponds, rivers and water sources, animals and the environment. The U.S Environmental Protection Agency has a search portal to find your local disposal facility. Or contact your local recycling center for steps on how to recycle it.

The bottom line is, muriatic acid is an ideal product for home restoration and maintenance projects, if you handle it with care and dispose of it properly.



Frequently Asked Questions

How do I properly dispose of unused muriatic acid?
Dispose of unused muriatic acid by contacting your local hazardous waste disposal service, as improper disposal can harm the environment and water sources.
Can you use muriatic acid on all pool surfaces?
While effective for balancing pH in pools, muriatic acid may not be suitable for all pool surfaces, especially for sensitive materials. Consult with a professional for specific surface compatibility.