It’s not fun when you have a clogged sink or drain because then you can’t use it properly, and the clog may only get worse the longer you leave it. Drano is often the go-to drain cleaner for many people—it works in 15 to 20 minutes—and just needs rinsing with warm water after that. But what if you leave Drano longer than 15 minutes or even overnight?

You can leave Drano overnight safely if you don’t do that every day. However, if you leave Drano for too long, it may damage the pipes, cause a foul smell and even release toxic gasses. In most cases, Drano will only damage your pipes if you use the product overnight frequently.

So, how long should you leave Drano to unclog pipes and drains? This article will answer all your concerns on using Drano and the possible side effects of leaving it for too long. I’ll also discuss alternative ways to unclog your drain without damaging the pipes, so read on!

What Happens if You Leave Drano in the Drain Too Long?

It’s not uncommon that you forget to flush the Drano with water after applying it, especially in the evening. Sometimes you may leave it in the drain for longer to clean more stubborn clogs. Some drain cleaners are designed to react more slowly, which is why they’re applied overnight for better results.

However, it’s not good to leave Drano in the drain too long.

Heat will build up and damage your pipes if you leave Drano in the drain for too long. Drano will react with the material stuck in the drain, resulting in heat and a distinct foul smell, like any other chemical drain cleaner would. In rare cases, leaving Drano for too long may worsen the clog.

If it’s your first time using Drano to unclog the drain, then leaving it for a bit longer than usual won’t cause significant damage to the pipes. Drano’s formula is milder than some of the industrial drain cleaners available in the market and won’t cause significant damage to your pipes immediately.

However, if you consistently leave it in the drain for too long, it’ll gradually damage the pipes.

Why You Shouldn’t Leave Drano in the Drain Overnight

You shouldn’t leave Drano in the drain overnight because it’ll slowly wear down your pipes and cause other damages, especially if you do it frequently. These include releasing toxic gasses in the air, leaving a foul smell, and potentially damaging your septic tank.

The following discusses what may happen if you leave Drano in the drain overnight:

Your Pipes Will Get Damaged if You Leave Drano Overnight

Drano is a strong cleaning chemical that produces heat when it comes into contact with dirt in the pipes. The damage often depends on how long you leave the drain cleaner in the pipes.

In most cases, damage only happens when the Drano sits in the drain for more than 10 to 12 hours. So, if you wash it down after 6 to 7 hours, it shouldn’t cause pipe damage.

However, in the case of stubborn clogs, it’s not advisable to leave Drano in the drain for too long. Drano has been known to harden the clogs and block the drain completely since the chemicals will react with different substances in different ways. If your drain is completely blocked, then it’s better to have a plumber clear it for you.

Drano That Sits in the Drain Too Long Can Cause Toxic Fumes

Leaving Drano in the drain for too long may cause it to release toxic gasses into the air, resulting in respiratory problems and eye irritation. How much gas is released depends on how badly your drain is clogged and what’s clogging the drain.

However, always use gloves and wear a mask when using Drano to unclog your pipes since it can be unpredictable. Drano can also cause skin damage if it comes into contact with your skin, so avoid contact and use it according to the recommendations on the bottle.

Leaving Drano Overnight in the Drain May Damage Your Septic Tank

Applying Drano once or twice won’t damage your septic tank, but using it frequently will. Since the septic tank contains bacteria that break down liquid waste, having too many chemicals in the tank will reduce its effectiveness.

If your drain gets clogged frequently, then you should consider getting a plumbing professional to fix it. In some cases, the Drano may only partially unblock the drain resulting in repeated blockages.

How Long Should You Leave Drano in the Drain?

You should only leave Drano in the drain for 10 to 15 minutes. The chemicals will react with anything clogging the drain and have it cleared in a few minutes. It’s best to follow this practice as recommended by Drano.

For tougher problems, you can leave Drano for 30 minutes, but not more. Leaving Drano for longer than 30 minutes won’t help unclog the drain any further since it only needs a few minutes to react.

If you use the Drano Build-Up Remover for routine maintenance, you can leave it overnight since it’s milder than regular Drano. However, you can’t use this product to unclog drains.

Where Can You Use Drano?

Drano is a drain cleaner.

You can use Drano in drains with PVC piping or metal piping. Using Drano to clean stubborn stains may be tempting, but never use it outside the recommended areas as it may cause damage.

Below are tips on where you can apply Drano:

Apply Drano to the Kitchen or Bathroom Sink

Drano works best for unclogging sink pipes, whether it’s the bathroom or kitchen sink. Kitchen sinks are usually made from stainless steel, and Drano won’t damage them. The same goes for ceramic bathroom sinks.

Make sure you don’t leave Drano too long in the sink.

Use Drano in Your Shower Drains

Shower drains will often get clogged with hair and may need to be unclogged every few months. A good drain cover should trap most of the hair and prevent it from blocking the drain. However, the shower drain may get blocked over time, and you’ll need to apply a drain cleaner to unblock it.

Drano is strong enough to burn through common materials that clog shower drains and may unclog the drain in less than 10 minutes.

Clean Your Bathtub Using Drano

You can also use Drano to clean bathtub drains as shower drains. When applying it in bathtub drains, ensure that you don’t leave any spills in the tub and wash it thoroughly before using the bathtub. Drano has toxic ingredients, so you want to make sure that your bathtub surface is clear from chemicals.

Where You Shouldn’t Use Drano

The only reason to use Drano is to unclog drains. There are certain places you shouldn’t use Drano.

You shouldn’t use Drano in toilets because the product is too harsh for them. Also, you shouldn’t use Drano for your floors, tiles, and other home settings.

Don’t Use Drano to Clean or Unclog Toilets

Never use Drano to unclog a toilet since the toilet’s drainage system is designed differently from a sink or regular drain. Always use a specialized toilet cleaner to clean your toilet. Always have a professional plumber unblock a clogged toilet to avoid damaging it.

Never Use Drano for Floors, Tiles, and Other Home Settings

Using Drano to clean a stubborn stain on your tiles or floors may be tempting, but doing this will only damage the floor. Drano is a strong drain cleaner that’s toxic and may cause skin and eye irritation.

If you have a tough stain to remove, use a specialized floor or tile cleaner instead.

How to Remove Drano From Your Drain

You can remove Drano from your drain or pipe by flushing it down with hot water. Warm water will work fine, but hot water will help flush any dirt that may be stuck in the drain. Suppose the drain is completely clogged, and the Drano won’t go down. Consider contacting a plumber to fix the clog.

Some people recommend unclogging drains with a plunger, but this could cause the harmful chemicals to splash over you. It’s also not a permanent solution to fixing the clog.

What Else Can You Do to Unclog Your Drains?

There are many alternatives to Drano for clearing up clogged drains.

You can prepare homemade baking soda or vinegar solution to unclog your drains —keep it mild if you worry the solution will damage your pipes. Bleach is an excellent option, too. Otherwise, you can always call a plumber to unclog your drains.

Plumbers will manually remove the dirt that’s clogging the drain. They’ll also check for leakages, pipe damage, and other issues.


Drano is a useful drain cleaning chemical used to unclog drains, pipes, sinks, and even bathtubs. However, many people make the mistake of leaving Drano overnight, which results in long-term pipe damage. You should flush down Drano with water after 15 minutes or a maximum of 30 minutes if the drain is completely blocked.

Never use Drano to unblock toilets or as a general cleaner. If your drain is completely blocked or gets blocked often, the best solution is to have it fixed by a professional plumber.

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