How to Fix a Slow Draining Kitchen Sink That is Not Clogged

Last Updated On September 20, 2022
How to Fix a Slow Draining Kitchen Sink That is Not Clogged

Do you have a slow draining kitchen sink, but you know it doesn’t have a clog? A slow drain can make simple chores more difficult, and potentially create unsanitary conditions.

It’s a frustrating experience when you know there isn’t a drain clog. Since we know you can’t live with a slow drain, we covered the potential causes of a slow drain and what to do about it. 

In this PlumbingNav guide, we will cover:

  • Problems caused by a slow drain
  • Causes of a slow draining kitchen sink (not clogged)
  • How to fix a slow draining sink

What's In This Guide?

      Slow Draining Kitchen Sink (Not Clogged)

      Most of the time a slow kitchen sink drain develops as a result of a clogged kitchen sink. However, when everything appears clear, you may find yourself somewhat confused about the actual cause. 

      Of course, you know you have a slow drain when you turn the water off yet it remains in the kitchen sink longer than usual. You may also notice a foul odor or gurgling sounds as the water drains. Here are some reasons why this may be happening.

      Causes of Slow Draining Kitchen Sink (Not Clogged)

      Clogged Drain Strainer

      A mesh drain strainer allows water to flow through small holes to your drain opening without letting larger items through. This can help prevent a clogged sink drain in the future.

      If these holes become clogged with soap scum, grease, or small food particles, water won’t drain as quickly. Clean out your strainer or place in the dishwasher if you use one. This is the easiest and most obvious place to start, but keep moving if this doesn’t apply.

      Vent Pipe

      Your plumbing vent pipes help regulate negative air pressure in your plumbing system. While water doesn’t flow through them, gases escape and new air is drawn in to aid the drainage process. If your vent pipes become blocked due to snow or debris such as a bird nest, it will reduce the air flow to your drain. This can restrict water flow and cause a specific drain to work more slowly.

      If there is a problem with airflow in your plumbing vent, you will likely know thanks to a gurgling sound coming from your sink. 

      Side note: Do you have a double sink? Try removing the drain stopper on one side if it’s a super tight seal. This may free up air to more easily move through the system if a vacuum is being created.

      did you know How to Fix a Slow Draining Kitchen Sink That is Not Clogged

      P Trap Problems

      You may not have a clog in your drain pipe but at your P trap before water reaches your drain line. This is also called a drain trap by some people.

      The P trap is a P-shaped component under your kitchen sink that always holds water and prevents sewer gas from entering back into the house. It also comes in handy to get something you want to get out of a sink drain, such as jewelry before it is lost and gone forever. 🙂

      A slow drain may indicate that your P trap requires cleaning. You should clean your P trap roughly every 3 months. If you never clean it, your drain will continue to be slow. You may also experience backflow. This is the most common part kitchen drain that experiences problems.

      Old Plumbing

      Old plumbing pipes can be the cause of your slow drain. Old pipes may develop rust or sediment buildup that can cause blockage. 

      While most pipes last 50 – 100 years, the lifespan of your pipes varies based on:

      • Pipe material
      • Maintenance routine
      • Amount of use
      • Items you put down the drain 
      • Water temperature 
      • Water pressure

      Tree Roots

      When trees want water, they spread their roots out to the nearest water source, which may be your sewer line. You will not see this occurring, but it can slow water progress over time as it tries to leave your drain system.A sewer line damaged by tree roots won’t drain properly since the airflow will be restricted. You can try a tree root killer for your sewer system, but we highly recommend using a sewer camera with a locator to first inspect the line if possible.

      How to Fix a Slow Draining Sink

      Plunge Sink Drain

      Use a plunger specifically designed for the sink to force pressure through your plumbing system, hopefully clearing the problem. 

      In order to plunge your sink properly, get a tight grip around the drain with the plunger when there’s a small amount of water still in the kitchen sink to cover the flange. Don’t forget to plug the overflow pipe with a rag if applicable. 

      When you have good suction on the drain, plunge up and down for about 30 – 60 seconds to see if you made any progress. 

      Drain Cleaning

      Even if you don’t believe you have a clog, you should clean your drain in case you have a clog that you cannot see. If you already used a product and assumed it worked, yet water is still slowly draining, don’t assume the clog was resolved.

      Some products work better than others, and sometimes clogs are deep in your drain pipes or somewhere you can’t see. Try using a powerful product like Drano Max Gel, or a more natural yet still powerful Green Gobbler.

      You can also start with a homemade drain cleaner made up of white vinegar and baking soda. This mixture is safe for your pipes compared to chemical drain cleaners and also inexpensive.

      Remove any Excess Grease or Oil Buildup

      Pour both the vinegar and baking soda down the drain. Once the materials mix, you should hear the reaction happening in your drain. After about 15 minutes, flush the drain with hot water. Boiling water can be fine in most cases, however, if your pipes are old let it cool a bit first.

      You may also want to try a plumbing snake. This is a drain opening tool that maneuvers through your pipes and clears the clogged pipe at the source. Drain snakes usually only reach about 25 feet into your pipes, though. 

      Don’t forget to clean the drain strainer, overflow pipe, and the P trap. 

      Flush Drain With Water

      Apply your sink stopper and completely fill the sink with hot water or boiling water and a small amount of dish soap. 

      Remove the drain stopper to allow the warm water to rush through the drain, hopefully resolving your problem. You can repeat this if needed.

      Still Have a Slow Drain? Inspect for Problems

      Start with a basic inspection of your visible plumbing components. 

      Look for leaks and other noticeable problems under the sink. You should also verify whether the slow drain only affects your kitchen or whether it affects your bathroom drain or shower drain, too. If it’s all drains, you’ll want to clean your main line.

      Since most problems occur deep in your plumbing system, you may need to call for a professional plumbing sewer inspection for a more detailed picture of the problem. 

      Problems Caused By a Slow Drain

      A slow drain is more than a pain! Here are just some of the problems that can occur due to a slow sink drain. 

      Mold 

      A slow drain means that water will remain in your pipes longer than usual. 

      The excess moisture creates ideal conditions for mold development, especially in warm weather. 

      Mold not only smells bad, but it also releases toxins into the air that can be hazardous to your family’s respiratory health. 

      Soap Scum and Hard Water Buildup

      Soap scum will remain in your sink and on your dishes when the water doesn’t drain quickly enough. 

      The standing water in your sink may also cause hard water stains, especially if you have water with high levels of magnesium, calcium, and limescale. 

      Sewer Line Issues

      A slow drain can lead to corrosion if you have older iron pipes

      Corrosion occurs more quickly when pipes are exposed to water, and when you have a slow drain, your pipes will have standing water in them more often. 

      Even if you have a plastic pipe, the extra water in the pipe can build up and create additional pressure on the pipes, leading to a leak.

      Final Thoughts on Slow Draining Kitchen Sink Not Clogged

      You didn’t put anything damaging down the garbage disposal, yet you still have a slow drain? Sometimes, the problem derives from somewhere else.

      With some investigation work and the right plumbing equipment, you should be able to identify and resolve the issue yourself. However, if you have found that you have damaged pipes further down your sewer line, you may need to call for professional pipe replacement services. Issues like these are tough to tackle as a DIY’er. We all need more help at times.

      Frequently Asked Questions on a Slow Draining Kitchen Sink (Not Clogged)

      How do you fix a slow draining kitchen sink?

      To fix a slow draining kitchen sink, you should start with an inspection of your plumbing. You should then plunge the drain and then perform standard drain cleaning to remove any grease buildup. Finally, flush the pipes with hot water. 

      Why is my kitchen sink not draining but pipes clear?

      Some of the main reasons that your kitchen sink may not drain properly even though you have clear pipes include:

      • Pipe damage
      • Clog in drain strainer, P trap, or overflow pipe
      • Air flow problem with vent

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      About Plumbing Navigator

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      About Plumbing Navigator

      We write about “all things plumbing,” helping you navigate common questions, repairs, and the best plumbing products on the market.

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