We’ve all been there. You just finished washing up a few dishes in your kitchen sink, or you’ve been rinsing them off prior to loading them in the dishwasher. Once the water goes down, the sink starts making some wicked gurgling noises. Perhaps the water is a bit slow in draining when you notice that the sink burps up a big bubble. Either way, the burp and the gurgling are caused by air that shouldn’t be there. The air in the pipe is trapped there by something. When this happens, a suction is created, pulling on the water in the P-trap, causing the sink noise made by the air trying to escape.
A gurgling sink or other sink noise may seem like just one of those things, but actually, it is a sign of a problem that is not going to go away, and will probably get worse as time goes on. It means there is a blockage somewhere, usually in the P-trap. The blockage is usually caused by things that shouldn’t have gone down the sink in the first place, such as hair or grease. Any stuck debris naturally collects more debris that sticks to the original lump, and the lump just keeps getting bigger until it’s removed. This is why plumbers recommend that only liquids go down the drain. Liquified hot grease doesn’t count, of course. Many people save empty cans or other containers for their grease and oils, disposing of them in the garbage when full.
Another cause of gurgling or a slow sink flow is something of which most people are not aware, and that is the vent pipe. Your plumbing system is vented by a pipe through the roof that prevents a vacuum from being formed in the drain system and keeps smelly gases flowing outward instead of backing up through the system. Tree or other debris can clog these vent pipes. People have even found dead birds blocking them. A plumber will be able to determine what is causing your problems.
For many common blockages, a large pot full of hot water poured down should melt grease and loosen whatever is stuck to it, allowing it to travel on. A large spaghetti pot will do nicely. You should use a second pot full 10 or 15 minutes later. There are many products on the market meant to dissolve the debris and allow it to flow on through. You do need to be careful when purchasing and using these products, however. Some can be very caustic, and some can actually eat through certain kinds of pipes, especially if the chemical is left in the pipe longer than recommended. Care must be taken to avoid any kind of contact between you and the chemical.
Plungers are another method of clearing clogs. They require about an inch of standing water to work well. They also work on the principles of pressure and suction, so if you’re working on a double kitchen sink, you’ll have to find a way to first seal off the other sink to use a plunger.
If your sink noise is caused by a clog that happens to be a little farther down the system than the P-trap, a drain snake is a great thing to have. They come in different lengths, usually 10 to 15 feet for home use. They are a long, flexible metal cable with a larger tip that looks like a spring. It’s threaded through your drain pipe while turning a handle to keep it turning around, catching debris as it goes. The trick is to not turn it too fast or the tip can brush over grease instead of catching it. They are great for catching hair clogs and do a fair job on grease as well, although it may take more than one trip for the snake to get enough of it inside the tip to cause the rest of the clog to loosen up. After finishing with the snake, flush the system with hot water for a few minutes.
If none of these methods help, your problem may be in the vent pipe or a clog may be farther down than a home snake can reach. At worst, an old pipe leading to the sewer or septic tank may be crumbling and causing a blockage. In any case, it’s best to contact a plumber before the clog completely blocks up your system and you get into panic mode.