How does Drano work?

The short answer

Drano's active ingredients create a series of chemical reactions to create heat and gas that breaks down the clog so it can flow through your pipes.

The long answer

We've all been there. You're minding your own business, washing the dishes, when the water that's supposed to be flowing down the drain starts to rise in your dirty, greasy sink.

Ugh.

This is when you might reach for a bottle of Drano, a common drain cleaner. You read the bottle, follow the instructions, and voilà: the sink starts to drain again. But how exactly does Drano work?

"​Drano bottles​" by ​Mike Mozart​ is licensed under ​CC BY 2.0​.

Drano's key ingredients include lye (sodium hydroxide), aluminum, salt (sodium chloride), bleach, and sodium nitrate. All these chemicals work together to break down grease, food, and hair to unclog your pipes.

Here's how Drano works:

Step 1: Lye, aluminum, and water react to produce heat.

Lye on its own starts to rapidly decompose the clog material. But when lye reacts with aluminum and water, it produces hydrogen gas, sodium aluminate, and (most importantly) a lot of heat.

Here's a clip from a demonstration of what happens when you combine lye, aluminum, and water. ​Click here to watch a video demonstration of this reaction​.

The near boiling temperature caused by this chemical reaction softens the grease and organic matter that's clogging your pipes. The hydrogen gas also bubbles up which loosens up the clog to help it go down the pipes. Finally, the salt is there to boost the chemical reaction and retain the high temperatures.

Step 2: Sodium nitrate removes the flammable hydrogen gas and produces ammonia and more lye.

While hydrogen gas helps break up the clog, it also is a fire hazard. Sodium nitrate reacts with the hydrogen to remove the flammable gas and produce more lye and ammonia. These chemicals continue to break down the clog.

Step 3: Bleach oxidizes the rest of the clog, converts ammonia into nitrogen gas and water, and eliminates odors.

Bleach is there to finish the job. When bleach comes into contact with the clog, it oxidizes the organic material. This means it "steals" electrons and breaks the material down into simpler, water-soluble molecules.

The bleach also reacts with the ammonia to convert it into harmless nitrogen gas and water. Finally, it disinfects the pipes and removes any unsavory odors.

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But despite Drano's 1960s slogan, "Once in every week, Drano in every drain," many plumbers advise against using Drano.

Why do plumbers say not to use Drano?

While Drano can be effective against many clogs, the intense chemical reactions can cause damage to your pipes, pose a safety hazard, and harm the environment.

Pipes older than 20 years and pipes made of PVC plastic may not be able to handle the heat from Drano. This can cause glue to melt and some pipes to crack or soften, causing a much bigger plumbing issue than a simple clog.

Additionally, there are safety concerns. If you don't properly rinse away the Drano, other chemical cleaners could continue to react with it and produce harmful fumes. Plus, if Drano splashes back up the pipes and on your skin, it can lead to chemical burns. Ouch.

Lastly, Drano needs to flow somewhere after it's done its job. The chemicals will make their way in the sewer system and potentially out to rivers, lakes, and oceans. Depending on where you live, this could cause damage to surrounding ecosystems and even the food supply.

So, how can you unclog your sink without using Drano?

Here are some other ways you can unclog your sink without using Drano:

1. Try a plunger: Plunge your sink 5-10 times and check if it worked. If not, pour some boiling water down the sink and try again. If you have a double sink, be sure to cover the second drain.

2. Try a drain snake: A drain snake is a long, flexible cable that can clear blockages deep in your drain pipe. Uncoil the drain snake until you hit the clog, rotate it until you feel the clog loosen, and then reel it back up to pull out the clog.

3. Try some at-home remedies:

   • Baking soda + vinegar + water: Pour 1/2 cup of baking soda into the clogged drain followed by 1/2 cup of white vinegar. Let this bubbling mixture sit for 20-30 minutes, and then pour boiling water down the drain. If you have a double sink, be sure to cover the second drain. The chemical reaction works to loosen up the clog and the water washes it down the drain.

   • Dish soap + water: Many clogs are caused by grease buildup, so soap can help get everything moving. Pour 1/2 cup of dish soap into the drain, followed by boiling water.

   • Salt + water: Pour 1/2 cup of salt in a circular motion so it covers all sides of the drain. Follow this up with boiling water.

4. Try an enzyme-based sink cleaner: Unlike chemical sink cleaners like Drano, enzyme sink cleaners use natural enzymes to break up organic matter clogging your pipes. This means they are safer for your pipes, your health, and the environment.

5. Call a plumber: When all else fails, get a professional to unclog your sink.

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Sources

GoodBee Plumbing. (2023, November 22). Best Drano Alternatives. GoodBee Plumbing. https://goodbeeplumbinganddrains.com/best-drano-alternatives/

Justia. (n.d.). ONCE IN EVERY WEEK DRANO IN EVERY DRAIN - Trademark Details. Justia. https://trademarks.justia.com/721/66/once-in-every-week-drano-in-every-drain-72166076.html

Kortes, J. (2020, August 19). Plumbers Say You Should Never Use Drano. To The T Plumbing, Heating & Air LLC. https://www.tothetplumbingandheating.com/post/plumbers-say-you-should-never-use-drano

Metro Heating & Cooling. (2021, May 18). Why Plumbers Hate Drano: What Homeowners Should Know. Metro Heating & Cooling. https://www.metroheating.net/why-plumbers-hate-drano-what-homeowners-should-know/

Wikimedia Foundation. (2024, October 10). Drano. Wikipedia. https://en.wikipedia.org/wiki/Drano