Slow Draining Kitchen Sink? 7 Sure-Fire Fixes

What Causes a Slow Draining Kitchen Sink?

A slow draining kitchen sink is basically a partial clog that is about to become a full clog (a sink that won’t drain at all).

slow draining kitchen sink

A slow draining kitchen sink is usually caused by fats, oils grease and foods that stick on the drainpipe and P-trap restricting the flow of water. It could also be caused by a clogged vent stack, which creates negative air pressure in the drainpipe.

A clogged garbage disposal could also be the culprit.

To fix a slow draining kitchen sink, drain it and pour ½ cup of dish soap down the drain then fill it with hot water. If that doesn’t work, pour a cup of baking soda followed by a cup of vinegar and after 30 minutes blast hot water down the drain.

Clean the P-trap to remove tough clogs. If it’s still clogged clear the vent stack.

When your kitchen sink won’t drain or is draining slowly but it is not clogged, clear your vent stack. A clogged vent means that air is not getting out of the system, and is forcing its way out of the kitchen drain.

How to Fix a Slow Draining Kitchen Sink

A slow draining kitchen sink is fairly easy to fix, unless you have a really nasty clog. The good thing is that you hardly ever need to buy anything, and if you do it is going to be pretty cheap.

In this post, I will give you a short answer and a long answer. Let us start with the short answer:

  • Remove Debris from the Drain Stopper: Check the sink’s stopper or strainer for food particles, grease, and debris. Remove and clean it thoroughly.
  • Use a Plunger: Place a wet cloth over the sink’s overflow opening (usually located near the top). Apply a plunger over the drain and create a strong seal. Plunge vigorously to dislodge clogs. Repeat as necessary.
  • Boiling Water: Pour a pot of boiling water down the drain to melt and flush away grease and soap residue. Repeat if needed.
  • Baking Soda and Vinegar: Pour a mixture of baking soda and vinegar down the drain. Allow it to foam and sit for a few minutes, then rinse with hot water to help break down clogs.
  • Use a Plumber’s Snake: Insert a plumber’s snake or drain auger into the drain to physically remove deeper clogs. Rotate and maneuver it as needed.
  • Check the P-Trap: Place a bucket or towel beneath the P-trap (the U-shaped pipe beneath the sink). Loosen and remove the P-trap to inspect for blockages. Clean it thoroughly and reattach it.
  • Natural Enzyme Cleaners: Consider using natural enzyme-based drain cleaners to break down organic matter within the pipes.
  • Check the Garbage Disposal: If you have a garbage disposal, ensure it’s functioning correctly and not contributing to the blockage.
  • Professional Help: If these DIY methods fail or if you suspect a more significant issue like a damaged pipe, consult a professional plumber for assessment and repair.

1. Use Hot Water and Dish Soap

As we have seen, a slow draining kitchen sink is attributed to accumulation of fats, oils and grease. In some occasions, it could be as result of hard water minerals deposits and especially calcium.

Hot water unlike cold water will dissolve or melt all the above substances. I always find it even more effective to combine hot water and a dish soap.

Think about it, if you want to clean an oily surface, hot water works perfectly with a dish washing solution. Doesn’t it? The dish soap provides proper lubrication, allowing the clog to slide down the drain easily.

Here is how to proceed:

  • Drain the sink. If you have cold water in the kitchen, scoop it out into a bucket until the sink is completely empty. You want the hot water and soap solution to act on the clog directly.
  • Pour ½ cup of dish soap down the kitchen sink drain. Let it drain slowly for 10 minutes. Some people prefer mixing the dish soap and the hot water. I think it is better if you pour the soap first and give it time to lubricate the clog. As you wait for the dish soap to lubricate the clog, boil about 2 gallons of water.
  • Pour the hot water in the kitchen sink all at once. The hot water will dissolve the clog while its weight will push it down the drain, and in the process unclog it.

2. Use Baking Soda and Vinegar

In her blog Blen Did, Blen argues that hot water and dish soap is a better method to unclog a drain than baking soda and vinegar. She even goes ahead and advises folks not to use vinegar and baking soda for the purposes of unclogging drains.

To drive her point home, Blen puts a scoop of butter in 2 separate bowls. On the first bowl, she adds hot water and dish soap and on the second one she adds baking soda and vinegar. The results as expected is that the hot water melts the butter while baking soda and vinegar do not manage to do it.

While I agree with Blen to some extent, her experiment missed some aspects of how to use baking soda and vinegar in unclogging drains. From experience, I know that baking soda and vinegar will unclog a slow draining kitchen sink or just any other clogged drain. But you have to do it right.

Here is how to unclog a slow draining kitchen sink with baking soda and vinegar:

  • Empty the kitchen sink completely. You can either use a vacuum or scoop the water manually into a bucket.
  • Blast hot water down the kitchen drain. Turn on the hot water faucet and run hot water down the kitchen sink drain for about 30 seconds. Wait a while as the hot water dissolves the clog.
  • Pour 1 cup of baking soda down the sink drain.
  • Slowly add a cup of vinegar down the drain. It is important to add the vinegar slowly as it reacts very fast with baking soda. Let the solution sit for 15-30 minutes.
  • Run hot water down the drain. Dump a gallon of hot water in the sink.

In most cases, you will find that the kitchen sink will start draining normally after the above process.

3. Inspect the Garbage Disposal

If you have a garbage disposal under your kitchen sink it could be the cause of your slow draining sink. This usually happens when you throw something that you shouldn’t through in the disposal, or run it for less time than it should be with less water as well.

If you have a double sink, check if both the sinks are clogged. If only the one with a garbage disposal is draining slowly then surely then the garbage disposal is the problem.

The first thing to do is to run the garbage disposal for 2 minutes with hot water running. If instead of draining quicker you notice that the garbage disposal is humming, it is a sign that something is jamming it or it is just broken.

Before attempting to troubleshoot a garbage disposal, always make sure that you unplug it from the power outlet. Another warning to abide by is to never stick your hand or finger to have a feel of how things are in the disposal.

Insert a long wooden stick in the disposal and attempt to spin the blades back and forth, in a bid to free them. If this does work, give the disposal about 10 minutes to cool off before turning it on

Although you can try to spin the disposal blades manually, in most cases that will not unclog it. This is often because the clog in most cases extends to the drainpipe and hence you need to unclog the drainpipe as well.

If the above is the case, duck under the kitchen sink and inspect the status of the plumbing. You will see a pipe (usually PVC) with 1 or 2 joints that connects the garbage disposal to the drain trap.

You need to disconnect this pipe (and perhaps even the drain trap) and check if there are clogs in there. In most cases you will find the pipes badly clogged.

The joints are often hand tight but if they are too tight us a wrench to loosen them. Always have a bucket below the connection to drain the water in the pipes.

4. Plunge the Sink

A drain plunger is an effective tool in dislodging drain clogs. It works by creating a pressure differential, where the pressure at the top of the clog is higher than the one below the clog forcing it to move down the drain.

There are 2 types of plungers. The first one is flat-bottomed and is used for most drains, and the bell-shaped plunger. The bell-shaped plunger is specifically designed for toilets so you need to get the flat-bottomed one.

Most people don’t know how to plunge effectively and that is why they have problems unclogging drains. Here is how to unclog a slow draining kitchen sink with a plunger:

  • If there is water in the sink drain it into a bucket, or wait for it to drain, albeit slowly.
  • Pour a little dish soap down the sink drain. This will help lubricate the clog.
  • Run the hot water for about 30 seconds then wait for 10 minutes. The hot water and the dish soap will start breaking down the clog, the plunger will just need to dislodge it.
  • Place the plunger over the sink drain and add some water. The base of the plunger needs to be immersed in water to create a better siphon.

Note: If you have a double-sink, you need to plug off the other sink’s drain otherwise the pressure generated by the plunger will escape through it. It is even better if you have a second plunger and have someone firmly hold it over the drain.

  • To plunge effectively, start by plunging gently to engage the plunger on the sink then the plunge aggressively for 2 minutes. Lift off the plunger to see if there is change in the rate of draining. Plunge more if needed.
  • Turn on the water just to be sure that the sink draining rate has been restored.

5. Snake the Drain

While there are many ways to clear a slow draining sink, snaking the sink drain is not one of my favorite. A snake drain has a spring-like and hooked head, flexible cable and a cranking handle. Some are motorized.

It unclogs drains by hooking and pulling out the clogs, or sometimes breaking them into smaller pieces. Why don’t I like it though?

Your kitchen sink drainpipe is plastic. It is very easy for the snake to create a hole in the drainpipe and you will have no alternative but to replace it. The best method to clear a nasty kitchen sink clog is to remove and clean the P-trap.

If you however want to give the snake a shot, you first need to be sure that you are feeding the snake in the sink drain with the P-trap. This is for people with double sinks. Check under your sink to see which sink drain is directly above the trap. That is where clogs are.

Feed the snake down the sink slowly until you encounter resistance. Crank the handle clockwise gently until you go through the restriction. Never force it down. Whenever it feels stuck/hard crank the handle in the opposite direction and start again.

If you don’t have a drain snake, a firm wire or wire coat hanger will do the trick. Straighten the hanger and make a hook on one end using a pair of pliers. Insert the hooked end down the sink drain and fish out as much gunk as possible.

Run down hot water after snaking.

6. Clean the P-Trap

A P-trap is the piece of pipe fitting under your kitchen sink that looks like an inverted P or U-shaped. Every fixture in your house with a drain has a P-trap, including your toilet and shower/tub.

A P-trap has 2 main functions:

  • It at all times holds a little amount of water. The water acts as a barrier, preventing sewer gas smells from coming up the kitchen. Any time you notice a sewer smell from any of your drain, often the trap is empty. Turning on the faucet is enough to fix the problem.
  • It “traps” clogs and hence prevent them from clogging the drainpipe further away where it would be difficult to unclog.

Any time you have a clogged or slow draining kitchen sink, the P-trap is often the problem. A clogged or partially clogged P-trap restricts the flow of water and hence a fully clogged or slow draining sink.

Although a clogged P-trap can be unclogged by the methods I have outlined above, some clogs will need to be physically removed. Here is how to unclog/clean a kitchen sink P-trap:

  • Clear the space. If you have things stored under your kitchen sink remove them to give you ample space to work with.
  • Gather your tools. You will need an empty bucket and a pair of channel locks. If you don’t have channel locks use whatever wrench you have available.
  • Place the bucket under the P-trap.
  • Your P-trap has 2 joints. One is higher than the other. You should start by loosening the lower one. This is to allow the water in the pipe to drain out by gravity.
  • Before jumping to use a wrench, make sure that the connections are not hand tight first. Only use a wrench if the connections are tight. Be gentle as the connections are usually plastic.
  • Once you loosen the connection, wait for the water in the pipe to drain in the bucket before completely removing the connection.
  • When the water has all drained, remove the P-trap and inspect its interior as well as the drainpipe that connects out of the P-trap. I am sure you will find gunk inside.
  • Since you cannot clean the P-trap in the sink, put water in a different container and clean it thoroughly. Clean the drainpipe with a wire probe as well.
  • Connect the P-trap back. Check if the draining rate of the sink has been restored. Don’t forget to check for leaks on the P-trap. If any tighten the connections a bit more, though gently.

7. Clear the Vent Stack

The vent stack is the vertical pipe which runs from your house’s drainpipe through the roof of the house. It allows sewer gases to flow out of the pipe and also allows free circulation of the air in all the house drains.

In order for your kitchen sink, toilet, shower or tub to drain effectively, there must be air in the drainpipe. If the vent is clogged, air will not flow out but will instead build up inside the drainpipe.

This problem will affect all the other house drains and not just the kitchen sink. You can sometimes also notice the kitchen sinks gurgling especially when the toilet is flushed or shower/tub drains.

Here is how to clear a clogged vent:

  • Climb to the roof of your house, a garden hose in hand.
  • Check if there is debris at the top that you can easily remove with your hand.
  • Probe the vent with the garden hose. If you feel something, have someone turn on the water to the garden hose. The weight of the water will most of the time unclog the vent.
  • If it doesn’t, upgrade to a drain snake.

How to Prevent Kitchen Sink Clogs

Kitchen sink clogs are 100% preventable. Just do through anything that you are not supposed to through down the drain. For people using garbage disposals with their sinks, please refer to the manufacturer’s manual to see what you can and cannot dispose.

This include things like:

  • Coffee grounds
  • Starchy foods like pasta, rice and bread
  • Fibrous fruits
  • Nuts and pits
  • Bones
  • meat
  • Egg shells
  • Potato peels

Pouring hot water down your kitchen drain also helps especially after doing dishes that were oily/greasy. For an even fresh smell, pouring vinegar and baking soda down the kitchen sink every once in 2 weeks is a good method.

Never used chemical drain cleaners in your kitchen sink if you have a garbage disposal. The chemicals will weaken the disposal’s rubber seals and it will start to leak after a short while.

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