Sink Backing Up From Neighbors [Causes and Fixes]

Sink Backing Up

This is usually caused when a pipe has a blockage inside it. There is a clog in the main stack below your unit. When your neighbor drains his sink, the water tries to get out of the blockage in the drain pipe. The pipe inside the stack will usually keep the water from getting out of the stack.

To find the clog or blockage in the stack, a plumber will need to remove the drain pipe, which should be done from inside the house. The backflow preventer should be tested when the plumber is working.

If the backflow preventer is working, it will prevent water from coming out of the stack. Your problem will be fixed by now. If the backflow preventer is not working, it could be the plumbing stack. Have the plumber inspect this part of your plumbing system.

Causes of Sink Backing Up From Neighbors

If you have a double sink, make sure the drainpipe is not clogged. Hair is one of the most common reasons for bathroom sink backing up. Check the drain line before you turn the water off. Some people use a vacuum, but it is not an option for a double sink.

This problem may occur when the drain pipe is not sufficiently deep. This is a quick fix that can easily be done by you. Be sure to have a plumber take a look at the drain line before you turn the water off. The problem will be fixed.

1. Clogged Hair

A clogged hair trap is the most common reason for sink backing up. It’s very common in bathrooms. The cleaning methods for hair traps are to unplug the drain and then remove the trap. If the hair trap is clogged, then you should use a drain snake. The drain snake should be held down the drain and then pulled up through the drain.


A hair trap is easily unclogged. You can also try using a piece of wire or a rubber stopper to press the hair trap to unclog it. If the hair trap is clogged, then you should clean the trap.

Clogged Hair in Sink

2. Clogged Grease or Oil

Clogs from kitchen sinks are caused by grease or oil. Pour boiling water directly into the sink to unclog it. Don’t pour the hot water down your drain. Clogs from your sink may be caused by a P trap or tailpiece that is clogged with debris. Check for debris or foreign matter in the sink tailpiece or P trap.


A plumber can help replace your sink. If the clog is in the tailpiece, it will need to be removed to unclog the drain. To remove the clog from the P trap, use a pipe wrench to unscrew the threaded cover and then open the P trap. If the P trap is plastic, you may have to replace it. The problem should be solved by now.

3. Clog in the Main Stack

The water is draining out of the main stack and the unit is not holding the water. As soon as the neighbor drains his sink, the water is backing up into your sink. This is the most typical cause of a clogged sink. The clog comes from the drain port that connects the main stack to the drain line.

It is important to flush the drain line frequently, and ensure that you have blocked up the drain ports. A plumber can inspect the stack for a clog that’s causing the problem. To do this, they will open up the drain line and then check the main stack for a blockage.

If they find any blockage, they can remove it, and the problem should be fixed. If the clog is from the drain port, they’ll replace the portion of the port. If it’s from the main stack, then they’ll have to replace the entire stack.


  • The first step to clearing a drain pipe clog is to remove the drain pipe cap (the sewer cleanout pipe).
  • The drain pipe cap is threaded and needs to be removed with a drain pipe wrench or pliers.
  • The drain pipe cap should be removed only after the clog has been loosened with a snake or drain line tool. This will prevent pressure and dangerous conditions for the drain pipe.
  • Once the drain pipe cap is removed, the water should flow back to the opening.
  • It is now time to insert the snake into the drain pipe.

4. Clog in the Main Sink Drainpipe

A curved drainpipe in your sink is another problem. It’s harder to clean and maintain than a straight drainpipe. Hair strands and other materials often get stuck in a curved drainpipe. If your drainpipe is curved, you’ll need to fish it out with a snake or plumber’s snake. A snake is a good option if you’re handy with a wrench.

Your problem can be fixed by proper maintenance of the main drain pipe. You’ll need to hire a plumber if this is a complicated job.


Pour one cup of fresh baking soda down the drain. Follow it with a cup of white vinegar. Place a sinkhole cover over the drain. Wait 15 minutes, then run hot tap water down the drain to clear the clog. If you have a clog, you’ll see lots of bubbles and lots of suds. Once the clog is clear, remove the drain cover and run hot tap water down the drain to clear the clog, and then replace the cover.

If the clog was too severe, replace the sinkhole cover. If the clog was caused by a buildup of hair, soap, or other items, you can use a plunger to clear it. If the clog was caused by a buildup of food or grease, you’ll need to use a drain cleaner. This is an inexpensive, easy way to clear the clog.

How to Fix Water Backing Up in Sink?

There are different methods, you can try, and which one works for you? Boiling water and garbage disposal are the most common.

Boiling Water

Attack with boiling water. Hold the left side of the sink and tilt the sink to the right. Tap the side of the sink until the water flows out. Remove the stopper and pour some boiling water into the sink. Please wait a few minutes for the water to cool before you use it for dishes or other purposes. Repeat these steps until the sink stops backing up.

Garbage disposal

To prevent this problem, make sure the garbage disposal is working properly. Squeeze the trap to see if water is flowing. If water is flowing, it could be a drain problem. If you don’t see any water flowing, the problem could be with the drain. If the disposal is clogged, it may cause a problem. If your garbage disposal is clogged, it should be replaced.

Plunge Away the Blockage

This is a common issue that occurs when the drainage plumbing is clogged. Some of the common causes of water backing up are A clogged drain. Backflow prevention valves. A clogged drain or toilet. Clogged garbage disposal. Malfunctioning garbage disposal. The first step to take if you notice water backing up in your sink is to plunge away the blockage.

Plunge away the blockage by inserting your hand into the drain and lifting it up and down until the water drains out. The water will be less than 3/4 of an inch deep. If the water is still backing up, remove the sink faucet and turn it counterclockwise until the water drains out. Toilet plungers are useful for plunging away the blockage.

Toilet plungers are also useful for getting water out of a toilet. Plunge away the blockage the same way you would if you were using a plunger. If you do not have a plunger, you can use your hand to plunge away the blockage.

Soda and Vinegar Method

Take a look at the outlet and faucet. If you find any obstructions, remove them. Press the drain valve to empty the pipes. Turn off the water supply to the sink and unplug it. Add a small amount of baking soda to the drain. Scrape the drain with a stiff brush to break up the clog. If the baking soda doesn’t work, then add a small amount of vinegar to the drain. Scrape the drain with a stiff brush to break up the clog. Rinse the drain with water. Plug the sink back in.

Clean the P-Trap

The P-trap is a small, square-shaped channel that feeds waste from your sink to your toilet. Dirty water will eventually find its way into this channel if the drain pipe is clogged. The first step to fixing this problem is to clean the P-trap. Use a small wire brush to remove any dirt particles.

Never use a metal pipe brush; it could damage the P-trap. Clean the P-trap with a solution of white vinegar and water. Use a clean rag or paper towel to wipe the solution off the P-trap. The process of removing dirt from the P-trap is called clearing the trap. Do not flush the drain line during this process. Scrub the P-trap with a clean rag or paper towel.

Can Upstairs Neighbor Cause My Sink to Back Up?

Make sure the sink is full. If you’re using a garbage disposal, make sure it’s turned off. The dishwasher shouldn’t be running. The stopper should be closed. Dirt and grime can get into the drain pipe and block it. Legally plumbing must be done as a specialty. You need a plumber who has experience working with sink drains.

Water Lines in Home

Toilets must be flushed at least once a week by a certified plumber. If you have a malfunctioning toilet, call a plumber. When you call the plumber, be prepared to describe your problem, and to pay in advance. You may also need to schedule a service call if your toilet becomes clogged.

PVC is very commonly used and it can be a difficult chemical to get rid of. It is even found in things that you might not realize were made from it like flooring. The PVC can end up in our groundwater system, which means it goes downstream and can cause problems.

PVC pipes can also crack and leak, just like any pipe. Even though PVC pipes are not generally considered a health issue, they can leak and cause problems in the ground.

To Recap

We’ve discussed the reasons and solutions behind the problem, sink backing up from neighbors. Try to fix it yourself by another method, or contact the HOA. I hope, they’ll fix your problem.

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