How To Use Lye To Unclog A Drain

Clogged drains are a nuisance, regardless of where they are. It might be a clump of hair in the bathroom drain or food scraps someone shoved down the drain. Either way, you’ll need to unclog the drain sooner rather than later before you can use the sink or tub/shower.

There are quite a few ways you can go about cleaning a drain, although some methods are more natural than others. Lye is certainly an option for unclogging drains, but it might not be your best bet. Here’s why. 

Can I Pour Lye Down The Drain?

Caustic soda, also known as lye, is a material used for various applications. Many folks use lye for making soaps and candles, as well as homemade biodiesel, various chemistry experiments, frosting glass, and specific food recipes. 

Lye is sodium hydroxide, which comes in liquid form, crystals, or flakes. This material is corrosive, making it a (mostly) effective way to clear clogs from a drain. While you can pour lye down the drain, many plumbers don’t recommend doing so, as it can cause more harm than good.

Will Lye Damage Pipes?

While lye does an exceptional job slicing through organic material (food scraps, hair, etc.), it sometimes does its job too well. As lye works, it generates heat. Due to this heat production, lye isn’t ideal for use in PVC or other plastic pipes, as it could potentially damage the plumbing. 

Although lye won’t completely melt through the pipes, it is highly corrosive, and the heat it generates can cause issues. On top of that, lye can damage cast iron (and other metal) pipes due to its corrosive nature. 

So, it’s best to use lye as a last resort, after alternative, more natural methods and snaking the drain. Even then, you should avoid using lye if the drain is completely blocked. If the drain is slowly draining, you might not notice adverse effects from the lye, but if the drain is completely blocked, the lye will sit. 

Lye is denser than water, so it’ll sink to the bottom of the basin containing standing water. However, the lye will accumulate near the clog if the drain is entirely blocked. The longer it sits in your plumbing, the more likely it is to damage it. 

Additionally, avoid using lye if you have a septic system. Septic systems operate using a finite balance of bacteria, so adding lye can throw off the function of the tank. Lye rapidly kills the good bacteria in the tank (which allows the tank to function correctly), so using it to unclog your drain can stop the solid waste breakdown in your system for up to 48 hours. After that, things will slowly return to regular function, but nobody wants to deal with a backed-up or non-functioning septic system.

How Long Does It Take For Lye To Clear A Drain?

Lye is a powerful drain opener, so it can take mere minutes to work. For example, a crystal lye drain opener with a 100 percent lye formula could burn through and dissolve hair, scum, soap, grease, and other scraps clogging the drain in roughly 15 to 30 minutes. 

How To Unclog A Drain With Lye

Unclogging a drain with lye isn’t a complicated process. However, lye is a caustic chemical, so you need to gather the correct materials to protect yourself. Here’s what you’ll need for the process:

  • Chemical-resistant safety glasses
  • Nitrile or latex gloves
  • Lye crystals
  • Bucket

Don Your Protective Gear

First things first, you need to prepare yourself before handling lye. Since it can cause all sorts of damage, you need to wear chemical-resistant safety glasses and a pair of nitrile or latex gloves while you handle the material. 

Once you have the necessary gear on, you’re ready to tackle the clog. 

Add Lye To The Drain

Next, you will add the lye to the drain to remove the clog. If you’re working with a sink or tub of standing water, wait until the water is cold. Lye produces enough heat to boil water, so you want to start with cold water instead of making hot water even hotter. If the water is warm or hot, give it time to cool. 

Once the water is cool, add about one teaspoon of lye crystals into the drain. Try to pour the crystals directly into the drain itself, as leaving the crystals on the bottom of the sink or tub can damage the surface. 

If there isn’t standing water in the basin you’re working with, follow the lye with a cup of cold water. Next, fit a bucket upside down over the drain. The bucket will prevent extremely hot, lye-filled water from splashing into the sink or on the surrounding items if it comes out of the drain. 

Let the lye work for 15 to 30 minutes. 

Rinse And Check For Draining

Lye is highly effective in most cases, so you shouldn’t have to do multiple treatments. However, some occasions call for a repeat process to remove tough clogs. You can do one more treatment before you should call it – if the second treatment doesn’t work, don’t continue adding lye to the drain. Instead, call a plumber. 

After 15 to 30 minutes, remove the bucket from the drain. If there’s standing water, you’ll need to repeat the process one more time. If there’s no water in the sink or tub, flush the drain with cold water. 

If you need to have a plumber handle the issue, be sure to tell them you used lye in the drain. This way, your plumber is aware of the chemical that could remain in the drain and can put on the proper gear to protect themself. 

Alternative Ways To Unclog A Drain

Lye isn’t the best approach to a clogged drain in many scenarios. So, perhaps your drain has a total blockage, or maybe you have plastic plumbing. Either way, lye isn’t the best option. Luckily, there are a few more ways to unclog a drain (all without fancy chemical drain cleaners):

  • Baking soda and vinegar: Pour a cup of baking soda and one cup of vinegar down the drain in question. Plug the drain with the stopper or cover, then let the mixture bubble for ten minutes. After that, remove the cover and flush the drain with hot (not boiling) water. 
  • Wire hanger: If the clog is within easy reach, use a wire hanger to remove it. Straighten the hanger into a long wire with a hook on the end. Insert the hook into the drain and attempt to grab the clog. Once you feel resistance, wiggle the hanger and rotate it to grasp the gunk, then slowly withdraw it from the drain. Remove the gunk, then repeat the process as needed. Flush the drain once the gunk is removed. 
  • Plumbing snake: A drain snake is a handy tool for tackling clogs further down the drain. Feed the end of the snake into the drain until you meet resistance. Once you feel resistance, turn the handle of the tool, causing the tip of the cable to grip the clog. Once you feel the snake break through the clog, slowly remove the cable. Remove any gunk from the cable and repeat the process as necessary. Flush the drain to remove remnants of the clog. 
  • Plunger: A plunger can be the perfect way to tackle the problematic clog in your drain. Remove the plug or cover from the drain opening, then position a plunger completely over the opening. Fill the sink with water until there are a few inches covering the plunger, then plunge vigorously. Remove the plunger to check for drainage. 

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