Can Bleach Unclog a Drain?

Cleaning and taking care of minor maintenance issues around the house are common tasks many of us do on a daily or weekly basis. Everyone seems to have a cupboard or shelf devoted to a menagerie of cans and bottles for different chores. Wouldn’t it be nice to know if one item in the collection could do multiple tasks? Bleach is used to clean counters and toilets, whiten clothes, remove stains, and disinfect surfaces, but can bleach unclog a drain?

Bleach is sodium hypochlorite, a chemical derived from salt. It can dissolve hair clogs in sinks, showers, or baths but isn’t great for clearing fat, vegetable, or toothpaste clogs in other drains.

In this article, we’ll discuss if it’s safe to dump bleach down the drain, if it will dissolve hair, and if it will unclog a drain. We’ll explain how to unclog a drain with bleach, how often to use it, if it’s better than Drano, or if vinegar is better. We’ll also identify other options for unclogging a drain. Hopefully, we’ll help you find a solution for your clogged drain.

Can Bleach Unclog a Drain

Is It Safe to Pour Bleach Down the Drain?

Pouring bleach down the drain is often discouraged as it can cause unforeseen damage. It can discolor your sink or drain, damage seals and gaskets, corrode different types of piping, or mix with other chemicals to produce toxic fumes or violent reactions. In small amounts or when diluted, bleach typically won’t damage your plumbing.

However, pouring a cup or two of bleach down a clogged drain in the hope that it will clear the clog, could lead to problems. Bleach is a powerful chemical that can corrode or damage copper pipes and fittings if left to sit for a long time. Even worse, if it doesn’t clear the clog, it is just sitting there waiting to mix with whatever else you dump down to clear it.

While bleach isn’t great for copper pipes, it doesn’t affect PVC or ABS pipes. Many people use bleach to disinfect the outside of the pipe under the sink, but the solution is typically diluted and wiped off with a damp rag or cloth after a few moments. Bleach can also be used to remedy algae growth inside ABS or PVC pipes, just ensure to pour lots of water down the drain afterward.

Drains also lead to someplace. If you drain leads to a septic tank, the bleach can kill the bacteria and other microorganisms that break down sewage and keep your septic system working properly. If the drain connects to the sewer and water treatment system, then bleach typically will be so diluted it won’t have an impact.

Does Bleach Dissolve Hair?

Hair from combing, brushing, trimming, shaving, or just showering or bathing can partially or fully plug a drain over time. This makes hair one of the major causes of clogs in bathroom sinks, showers, and tub drains. Bleach is a base chemical and hair is considered to have acidic properties, so bleach will dissolve hair. Thus, bleach may be used in a bathroom drain to dissolve a plug caused by hair buildup.

Can Bleach Unclog a Drain?

Does Bleach Dissolve Hair

Using bleach to clear a clogged drain depends on the type of plumbing pipe and where the clogged drain is located. Blockage typically occurs in the trap under a sink, shower, or tub. The trap typically remains full of water to prevent sewage or septic gasses from escaping into the house. Additionally, the trap also tends to catch items that fall down the drain, like hair, food, grease, rings, and earrings.

Bathroom sink drains commonly collect hair and toothpaste residue, while the shower and bath drain usually only collect hair. Kitchen sinks, however, often catch vegetable matter, food fat and oils, bread crumbs, and other organic material that is washed down the drain. Over time, that collection can partially or fully block the drain. So, if the clog is located in a bathroom drain, it will commonly be caused by hair, while a kitchen clog is mostly food matter.

A clog located in a bathroom sink, shower, or tub drain, since it is mostly caused by hair, and bleach can dissolve hair, should effectively be cleared by bleach. However, make sure the house is connected to a municipal sewage system and not a septic system. Additionally, it is best if the drain pipe is ABS or PVC and not copper, since bleach can damage copper and brass fittings. Be aware though, that bleach can dissolve some ABS and PVC glues.

How To Unclog Drain With Bleach

Using bleach to unclog a drain is one of many home remedies. Since bleach dissolves hair, it’s best to use it in a bathroom sink, shower, or tub. Bleach can also kill bacteria and improve the smell emanating from your sink’s drain. However, bleach isn’t recommended for drains if your home has a septic system.

Safety Precautions

Bleach is a corrosive liquid and can irritate skin, damage eyes, and cause respiratory issues for some. When using bleach, it is best to wear rubber gloves and eye protection, and a respirator if bleach fumes cause respiratory concerns.

Measurements and Steps

  • To unclog a bathroom drain, remove as much excess water from the sink, tub or shower as possible.
  • Pour one cup of bleach into a measuring cup, and then pour it directly down the drain if possible – the goal is to reduce splashing and thus risk of injury.
  • Set a timer and wait for 10 to 15 minutes – any longer can cause damage to metal drain components.
  • Pour or run hot water down the drain for 5 minutes to flush the bleach out of the pipes – provided the bleach unclogged the drain.

Expected Results

The bleach should improve the flow of water down the drain, provided the clog is caused predominately by hair. It will also improve the drain’s smell and brighten your sink. If the bleach didn’t work, the warm water would help dilute the bleach and reduce its corrosive abilities. Try a different method or contact a plumber.

How Much Bleach Does It Take to Clear a Drain?

Most sink, shower, or tub drainpipes are 1-1/4” or 1-1/2” in diameter, and all have a trap to prevent sewage or septic gasses from entering the living area. The amount of water typically contained in the trap varies, but 8oz (1 cup) of undiluted bleach should be sufficient to fill the airlock portion of the trap. The further the trap is from the drain, though, the more water that could be held in the connecting pipe if the trap is clogged.

Bleach is heavier than water, so it will sink to the clog. Unfortunately, the more water it passes through, the more diluted it will become, making it less effective. Therefore, it is necessary to remove as much trapped water as possible to get the full effect of the bleach on the clog.

How Long Can Bleach Sit In Drain?

The maximum amount of time bleach should sit in a drain is 15 minutes, any longer and it can begin to corrode metal, deteriorate rubber and synthetic seals, and damage porcelain. The recommended amount of time for bleach to work to clear a hair-clogged drain is 10 minutes. The cleared drain should be flushed with warm water for 5 minutes to ensure the bleach is gone and diluted.

How Often Should You Pour Bleach Down Your Drain?

A quick canvas of the internet gives answers ranging from once a week, once a month, every 6 months, to never! Bleach diluted in water is a disinfecting solution used to sterilize surfaces and kill bacteria. Unfortunately, it is also corrosive to metals, rubber and synthetic seals, porcelain, and other materials, especially if it is allowed to sit too long. Thus, most manufacturers recommend rinsing with clean water or wiping surfaces down with a clean damp cloth after using bleach.

Pure or diluted bleach poured down an unclogged drain does improve the smell emanating from the drain, plus it will kill bacteria, mold, and mildew it encounters, and help remove the black slime that commonly lines drains. Undiluted bleach will also dissolve hair caught in the trap and help to prevent potential clogs.

Having read all that, if you’re on a septic system or have metal drain pipes you should never pour bleach down the drain. It will interfere with the good bacteria at work in the septic tank and corrode your drain pipes. If the house is connected to municipal sewers and has PVC or ABS drain pipes, you can use bleach down the drain, just make sure to flush with clear water for 5 minutes.

The frequency of use, however, typically depends on the individual. Some commercial kitchens dump diluted bleach down the drains every day. Most residences that use diluted bleach to clean and sterilize, empty the bucket down the drain following their weekly cleaning. With this in mind and the fact that it has been going on for decades without causing floods, pouring a diluted bleach solution down the drain on a weekly basis should be fine.

Can Bleach Unclog a Kitchen Sink?

Bleach will disinfect surfaces, improve smells, and dissolve hair. However, it does not dissolve fats or grease, bread crumbs, vegetable waste, or other organic matter commonly found in clogged kitchen drains. Therefore, bleach won’t work to unclog a kitchen drain, although it can make it smell better.

Is Bleach Better Than Drano?

Drano Max Gel Drain Clog Remover and Cleaner for Shower or Sink Drains, Unclogs and Removes Hair, Soap Scum and Blockages, 80 OzBoth bleach and Drano can damage drain pipes. Bleach is sodium hypochlorite which is derived from salt. It kills bacteria and dissolves hair. Bleach is a common household cleaner and a cup of undiluted bleach can be used to unclog drains plugged by hair.

Drano contains lye, aluminum, sodium nitrate, bleach, and salt. The chemical mixture creates an instantaneous reaction that compresses and dissolves organic material and produces a rapid temperature increase that can cause plumbing to crack or melt, and plumbing seals and glues to dissolve. Since it contains bleach, it also shouldn’t be used in homes with a septic system.

Both bleach and Drano can cause skin, eye, and respiratory issues. They also both need to be flushed with hot or warm water following use. While Drano will work better on a kitchen clog, bleach is the better of the two for bathroom drains and your home’s plumbing.

Vinegar or Bleach for Drains: What Is Better?

VinegarVinegar, by itself or diluted in water is a common cleaner that is less corrosive to metals and plastics, and less irritating to eyes, skin, or the respiratory system. It is also safe to use down the drain in homes connected to a septic system. This fact alone tells us that it doesn’t kill all bacteria as bleach does.

Using vinegar by itself or diluted in water can keep a drain smelling nice, but it won’t clear a clogged drain. Using it in conjunction with baking soda, however, will create a bubbling solution of carbon dioxide that can loosen and break up clogs. The reaction also generates pressure, which, combined with gravity, can remove the clog.

Most recipes for using vinegar call for boiling water to be poured down the drain, once it has seeped through, dump a cup of baking soda followed by a cup of vinegar down the drain, and cover with a plate or the plug. Let the reaction work for 20 to 30 minutes, and then pour another kettle of boiling water down to flush the clog and drain clear.

Bleach is better for clearing bathroom drains that typically clog from hair. Vinegar, combined with baking soda, is good for both kitchen and bathroom drains, and even those connected to septic systems. Vinegar is also safer for pipes, seals, and the environment. Bleach is a disinfectant; vinegar is not.

Other Drain Unclogging Options

Drain Unclogging Options

If bleach won’t work or you can’t or don’t wish to use it, there are numerous options for unclogging a plugged or partially plugged drain. Some are really simple; others require a little bit of work. Here are 10 options for unclogging a drain.

Boiling Water is the simplest and least expensive solution. Since many kitchen clogs contain hardened fat and grease, pouring boiling water down may soften its hold and dissolve and dislodge the clogging material. If it doesn’t work, remove the water once it has cooled and try another method.

Wet-Dry Vacuum is another possible way to remove a blockage from a drain. Cover the sink or tub overflow vent, and place the nozzle in the drain. Use plastic wrap or something similar to create a seal to block air into the drain around the nozzle. Turn the vacuum on and hopefully, it will draw the blocking material up. Flush with water afterward to see if it was successful.

Dish Detergent and Boiling Water are another potent de-clogger. Pour 1/4 to 1/2 a cup of dish soap down the drain followed by boiling water. The soap is slippery and acts as a degreaser to break up fats, while the boiling water helps dissolve fatty material too. Let the mixture work for 5 minutes, and then use a plunger to help dislodge if necessary.

Wire Hangers have many uses. Straighten a hanger and bend a tight hook at one end, insert the hook end into the drain and attempt to dislodge or fish out debris. The focus is on pulling muck out, not pushing it deeper down the drain. Once some debris is removed, try the boiling water again.

Drain Snakes come in a variety of materials but typically have a flexible shaft with barbs or bristles at one end. They operate similar to the bent hanger, except the flexible shaft works better in the trap. Work the barbed or bristle end down the drain and into the clog, pulling it back up catches and draws clogging material up. It may take several fishing excursions to catch and remove all the blockage. This method works well even through a sink or tub full of water.

Baking Soda and Vinegar generate a bubbling solution that loosens and breaks up the clog. Pour boiling water down the drain, let it seep through, then dump a cup of baking soda followed by a cup of vinegar down the drain, cover the drain with the plug, and wait 20 to 30 minutes. Remove the plug and pour another kettle of boiling water down to flush the clog and drain clear.

Salt and Baking Soda is another combination that works well to dissolve blockages. Mix 1/2 a cup of each and pour down the drain, let sit for 10 to 20 minutes and then pour down boiling water.

Caustic Soda or sodium hydroxide is a harsh chemical so wear personal safety protection. Stir 3 cups of the caustic soda into 3/4 of a gallon of cold water – the mixture will heat up and fizz. Pour down the drain and wait for 20 to 30 minutes before flushing with boiling water. It may take several attempts before the drain is fully cleared.

P and S-Traps are common in many kitchens and bathroom sink drains. Many have a coupling at both ends, and some have a drain plug at the lowest curve of the trap. If you decide to remove the trap or drain plug, place a bucket under it first. Remove the plug or trap, clean out the blockage and reconnect. Pour water down to ensure the problem is solved and that there are no leaks before removing the bucket.

A Plumber is another option. They are the professionals and a call to them may solve the problem quickly without a huge price tag. You may want to call on them first if you think you might make the problem worse trying to fix it yourself, which could result in a larger price tag.


Bleach can dissolve hair clogs in sinks, showers, or baths. Unfortunately, it isn’t good at clearing fat, vegetable, or toothpaste clogs. Bleach also kills bacteria, so it shouldn’t be used in drains of homes with septic systems, only those on municipal sewage systems. Hopefully, we’ve provided you with the information you need to get your drains flowing as they should.

Written By: Yevgen

YevgenI'm a DIY nut, and the founder and chief editor here at Weekend Builds.
This site is a result of my DIY passion, and to share the joys I have experienced fixing, building, and creating things over the years.

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