If your kitchen sink seems to clog constantly even after you plunge or snake it, then there’s probably something in the pipes beneath it. Unfortunately, several of the materials homeowners flush down their kitchen drains can build up on pipe walls over time until they create stubborn, pervasive clogs.

Obviously, the first thing to do is stop making these clogs worse! To do that, you’ll have to figure out what you’re flushing and how to deal with it differently. Here are the four main reasons why your kitchen sink keeps clogging, and why they’re an issue in the first place:


Cooking oil pouring into a plastic container

Fats, Oils and Grease. These are the three most infamous kitchen sink cloggers out there. Unfortunately, they’re also the most common. The problem is, these substances are all perfectly suited to clogging drains. For one thing, they’re sticky. FOG rarely makes it all the way down your drain; instead, they tend to get stuck to the sides of your drains partway through. Worse, once they’re stuck to the sides of your pipes… they harden.

As FOG cools, it congeals and hardens. Hard FOG can restrict or even completely block waterflow. Plunging can clear out the worst of a FOG clog, but it usually can’t blast the residue from the pipe walls. The next time you flush a little more FOG, it’l stick to the remaining residue and form the clog again. Avoiding these clogs is simple: never pour fats, oils, or greases into your kitchen drain again!

Coffee grounds

Coffee grounds

This is another bummer: coffee grounds are terrible for kitchen sinks. Even if you have a garbage disposal, you should neither dump grounds down your sink nor even allow them to drain accidentally. Once they’re in your pipes, coffee grounds can collect over time to make particularly stubborn and pervasive clogging problems–especially if they catch other particles on their way down. The problem with coffee grounds has to do with what happens when they get wet.

Think about what happens when you pour water over grounds when you make your coffee. They absorb water, clump up together, and get sticky. This is exactly what they do in your pipes, too. Like FOG, coffee grounds can get stuck to the sides of your pipes and congeal, forming the basis for future clogs. Even worse, they tend to catch other material that passes through your pipes, triggering sudden, annoying small clogs constantly.

Food remains (even if you have a garbage disposal)

Rice and beans

A lot of homeowners assume that if you have a garbage disposal, throwing any food into it is fair game. We’re sympathetic, but unfortunately this just isn’t the case. Garbage disposals are for fruit and vegetable and vegetable scraps, small bones, ice, and cooked meat. There are a lot of foods that could create clogs even if you use a garbage disposal on them.

In particular, never throw potatoes, rice, or beans down your disposal. These foods swell up when exposed to water. After running through your disposal they become a kind of paste that can (you guessed it) stick to the sides of your pipe walls. Eggshells, large bones, raw meat, and shells are a no-go, too; not only can these cause clogs, but they damage your disposal on the way down.

P-trap problems

P-trap under a sink

The p-trap is the curved pipe directly beneath your sink that connects the drain to the rest of your deposit pipes. It’s called a “p-trap” or sometimes an “s-pipe” because of its distinctive “p” or “s shaped” curve. The p-trap curves to hold a little water in order to block sewer gases from rising back up through your drain. Unfortunately, however, it occasionally becomes an obstacle certain objects just can’t pass.

If your kitchen sink keeps clogging or drains very slowly, there’s a chance something’s stuck in your p-trap. Put on some gloves, grab a bucket, and remove the p-trap carefully. Most p-traps have fasteners that can be twisted loose by hand, but you may need a wrench. Expect some dirty water to fall out when you turn it. Check the inside of the p-trap for either objects or buildup, and then clean it out thoroughly.

These are the most common reasons why your kitchen sink keeps clogging, but they are not the only possibilities by any means. Unfortunately, your kitchen sink–or even your pipes in general–could have all kinds of issues that could lead to constant clogs.

Luckily, no matter what these issues may be, you have options. If you can’t seem to isolate and correct your clog problem, you can always call the experts at Ben Franklin Plumbing. We’ll figure out what’s happening with your kitchen sink and fix it punctually–it’s in the name, after all.