Using Muriatic Acid to Clean Drains

gloved hands with plunger and liquid above small metal sink
What You'll Need
Face mask
Safety goggles
Muriatic acid
Glass measuring cup
Baking soda
What You'll Need
Face mask
Safety goggles
Muriatic acid
Glass measuring cup
Baking soda

Muriatic acid is very effective for cleaning drains, although it should probably only be used after all else fails. The fact that it’s acid, more specifically a type of hydrochloric acid solution, means that it needs to be used with very great care to ensure that it does not cause any damage to you, the surrounding area, or the drain in question that you are looking to clean.

When you use muriatic acid for cleaning a drain, protect yourself thoroughly by wearing heavy gloves, safety goggles, and a face mask to prevent the acid from accidentally splashing into your eyes or onto your skin, to avoid touching your hands to your face, and use an appropriate respirator to avoid inhaling fumes.

You should also open a window if possible or run a fan in the area. This will prevent the fumes from staying in one small area and make it easier for you to breathe fresh air as opposed to the fumes caused by the acid you are using to clean the drain.

Even if you are only using a small amount of muriatic acid, do not skip taking the necessary safety precautions. Spending a little time on your safety will make a huge difference in the long run and protect you from any issues that could occur during the course of your cleaning project.

How Muriatic Acid Works

Muriatic acid is exceptionally strong and works by causing a chemical reaction with the items that are blocking the sink. The reaction creates heat, and that is what breaks up the blockage. It works fairly quickly, so expect a solution much more quickly than with other methods you might try.

It can’t be stated too strongly that muriatic acid is dangerous and needs to be used with safety equipment and according to the manufacturer’s instructions. As previously mentioned, there are safety precautions you must take before you start to use muriatic acid in order to ensure your safety.

When to Use Muriatic Acid

Muriatic acid can be used to clean out blocked drains but should not be the first thing you do to try to clean a blockage. As mentioned previously, start out by using gentler solutions to clean out your drains if they’re clogged.

These will remove small clogs and also clean the drain. If that doesn’t work, move to progressively stronger methods to see if they will do the job. Only when all the other methods have failed and you’ve determined that the clog is a very bad one should you move to muriatic acid.

You could also call a plumber instead who will be able to rid your drain of clogs and make suggestions for how to prevent similar clogs in the future.

Prepare Yourself and the Area

You need to use muriatic acid in a well-ventilated room. Ensure that the windows are open, even if it’s cold outside, since the acid fumes can burn your throat if the room isn’t properly ventilated. If the area has an overhead fan, you should also run that as you work.

Before you begin, you must also put on gloves, a mask, and safety goggles before opening up the acid. You should also wear long sleeves to protect your skin from any acid splashes. Do not skip this step

If your drain has a metal grating, use a screwdriver to unscrew it and set it aside. Muriatic acid can damage some metal, so it's best not to pour it through a grate.

Make sure you do not misplace any of the screws. You will need to use those to screw the grating back into place after you have cleared the clog out of your drain.

Using the Acid

For household purposes, you should never use muriatic acid without diluting the solution with water. This substance is very corrosive and if applied directly down the drain, your pipes may end up seriously damaged.

Also, note that muriatic acid should always be added to water—rather than the other way around—to avoid splashing and a potentially dangerous reaction.

In order to dilute the muriatic acid, measure out one-half cup of water into a glass measuring cup; don’t use plastic for this as the acid can eat at the cup and damage or even destroy it.

Add your muriatic acid to the water in the cup carefully. Pour the diluted solution into the clogged drain, and leave it there for about 10 minutes. During this time the acid will work on the clog, heating it up, and breaking it up as promised.

After the 10 minutes have elapsed, turn on the cold faucet and let the water run down the drain. The muriatic acid should have cleared the clog by this time, and your drain will be clean. Make sure to run the water for at least a few minutes to give it a chance to really wipe down all of the muriatic acid.

If at First, You Don't Succeed

In the event that muriatic acid doesn’t work to unclog your drain, you can try repeating the procedure but only one more time. Doing it too many times can damage your drain since muriatic acid is an acid.

Once more, put the acid down the sink and wait for 10 minutes before flushing with cold water. A second application should shift virtually every clog in a drain, but if, however, it doesn’t, then you’ll need to have the drains rodded. You can either do this yourself or employ a professional plumber to do so.

However, DO NOT try using muriatic acid more than twice on a clog, or you will risk damaging the pipes and the drain, perhaps even beyond repair, which can be a much costlier fix than simply paying a plumber to unclog your drain for you.

Can I Use Muriatic Acid to Unclog a Toilet?

If you have successfully used muriatic acid to unclog a drain, you may be wondering if it can also be used to unclog a toilet. The answer is yes, muriatic acid can be used to unclog a toilet.

Like with the drain, though, you must take safety precautions when using muriatic acid. In order to use it, start by putting on property safety gear including goggles and gloves. Then start to ventilate the bathroom.

Now, you can mix one part of muriatic acid in with five parts of water to dilute it. As previously mentioned, add the muriatic acid to the water, not the other way around.

Once you have done this, you can slowly start to pour the diluted solution into the toilet bowl. Add only a small amount, roughly enough to come up to the normal water level of the toilet bowl.

Once the solution has been added, let it sit in the bowl for a few hours. After that, you can flush it down.

This should resolve the clog in the toilet. If it doesn't, it may be time to call in the professionals to handle the task instead.

Does Muriatic Acid Corrode PVC?

You may be wondering if muriatic acid can corrode PVC pipes. The short answer is that muriatic acid, if used incorrectly, can damage any type of drain.

This is why it is important to dilute the muriatic acid in water before using it. This is also why you should not use muriatic acid often. It should not be part of your everyday maintenance. Instead, it should be used only when other methods of clog removal fail. It is a last-ditch drain clog removal option, not the first thing to try.

How dangerous the fumes can be as well as the acid if it touches you are other reasons why muriatic acid should only be used if all else fails.

So yes, muriatic acid, when diluted, can be used with PVC pipes without damaging the pipes but should not be used unless it is necessary to do so.

Will Muriatic Acid Damage Copper Pipes?

Muriatic acid can be used in homes with copper pipes much like it can be used in homes with PVC pipes, but only if the necessary precautions are taken. Never forget to dilute the muriatic acid before using it and always wear protective gear and make sure the space in which you are working is as well-ventilated as possible.

If you start to feel dizzy or light-headed at any time during the project, take a break and get some fresh air.

Too much muriatic acid, just like too much of any type of acid, can damage pipes so be careful when using muriatic acid to get rid of a clogged drain.

If your copper pipes are old, you may need to take some extra safety precautions which would mean not using muriatic acid. If you live in an old home or a home with old plumbing, it may be beneficial to call in a plumber rather than using muriatic acid.

Once the plumber is there and resolves the clogging issue, you could always ask him or her if muriatic acid would work in the future to resolve similar issues.

What Is the Best Chemical to Unblock Drains?

There are a number of chemicals out there that can be used to unblock drains, both by individuals and professionals. Chemicals such as Draino are used by many because they are easy to use and relatively effective.

Muriatic acid is another favorite for the reasons mentioned above.

No matter what chemicals you use to unblock your drain, though, make sure to carefully read the labels on the chemical agents to make sure you are applying the correct amount and using the product properly.

While you can use acids to unlock drains, it can harm the pipes if not used properly or if too much is used so make sure to be cautious when you are using chemical products.

Can You Pour Acid Down the Drain?

The simple answer here is yes, you can pour acids down the drain. There is a caveat, however, you must use the acids properly and never use too much of them.

Using too much acid can damage your plumbing beyond repair so make sure not to use too much. In the case of muriatic acid, you will need to severely dilute the chemical before using it on a clogged drain. You can use the solution twice if need be, but do not use it more than that because you risk harming your plumbing.

Muriatic acid, like other chemicals, should be a last resort and not a first attempt at unclogging a drain. If all else has failed and you don't want to call in a plumber just yet, however, muriatic acid can be a great solution for a clogged drain when used appropriately.

Just make sure using it is not a regular occurrence and that you take great care to follow the correct safety procedures when using muriatic acid in your home in order to unclog a drain that you could not fix through other unclogging methods.

If clogged drains are a common occurrence, you may want to call in a plumber to see if there's a bigger issue at play, or invest in a device to block hair from going down the drain which can cause a lot of issues, especially in older, smaller pipes in some bathrooms and other areas of the home.


Muriatic acid can be a great way to rid your drain of any and all clogs. It is, however, an acid and can be a bit dangerous. If you decide to use it, make sure to follow the necessary safety precautions.

Doing so is incredibly important for both you and the health of your plumbing. Not following property safety advice can not only not rid your drain of the clog, but can damage your pipes and hurt you.