If your upstairs kitchen sink won't drain, the first thing you should check for is a clogged drain. This is a common issue that can be caused by a variety of things, such as food debris, hair, and soap scum. To clear a clogged drain, you can try using a plunger or a drain snake. If these methods don't work, you may need to call a professional plumber to use more advanced techniques, such as hydro-jetting, to clear the clog.1. Clogged Drain
Blocked pipes are another common cause of an upstairs kitchen sink that won't drain. This can be caused by a variety of things, such as foreign objects, tree roots, or even frozen pipes in colder climates. If you suspect that your pipes are blocked, it's best to call a plumber to properly diagnose and fix the issue.2. Blocked Pipes
Over time, grease and oil can build up in your kitchen sink pipes and cause blockages. This is especially true if you frequently pour cooking oil or grease down your drain. To prevent this issue, it's important to properly dispose of grease and oil by pouring it into a container and throwing it in the trash, rather than down the drain.3. Grease Buildup
If your kitchen sink has a garbage disposal, a broken or malfunctioning unit could be the cause of your sink not draining properly. A faulty garbage disposal can cause food debris to get stuck and create a clog. If you suspect your garbage disposal is the issue, it's best to call a professional to repair or replace it.4. Broken Garbage Disposal
If your kitchen sink has a stopper, a faulty one could be preventing the sink from draining properly. This can be caused by a worn or broken stopper, or a problem with the mechanism that controls it. In most cases, a professional plumber can easily replace a faulty drain stopper.5. Faulty Drain Stopper
If your kitchen sink won't drain, you may have a leak in your pipes. This can be caused by a variety of things, such as corrosion, loose connections, or damage. Not only can leaking pipes cause issues with your sink draining, but they can also lead to bigger problems, such as water damage. It's important to address any leaks in your pipes as soon as possible.6. Leaking Pipes
In some cases, tree roots can grow into your sewer line and cause blockages. This can be a difficult issue to diagnose and fix on your own, so it's best to call a professional plumber to properly assess and resolve the issue.7. Tree Roots in Sewer Line
Over time, pipes can become corroded and damaged, which can lead to blockages and other issues. This is especially common in older homes with outdated plumbing systems. If you suspect that your pipes are corroded, it's important to have them inspected and replaced if necessary.8. Corroded Pipes
A properly functioning plumbing system requires proper venting to allow air to flow and prevent suction that can lead to clogs. If your kitchen sink won't drain, it could be due to improper venting, which can be caused by a variety of factors. A plumber can properly diagnose and resolve any issues with your plumbing venting.9. Improper Venting
If all other options have been ruled out and your kitchen sink still won't drain, it's possible that there is a backup in your main sewer line. This can be caused by a variety of things, such as tree roots, debris, or a collapsed sewer line. A professional plumber can use advanced techniques, such as sewer camera inspections, to diagnose and resolve the issue. In conclusion, if your upstairs kitchen sink won't drain, it's important to properly diagnose and address the issue to prevent further damage and inconvenience. By understanding the common causes of a clogged sink, you can take the necessary steps to prevent and resolve any issues that may arise. Remember, when in doubt, it's always best to call a professional plumber for expert assistance.10. Sewer Line Backup