Why Am I Hearing Toilet Flushing Through My Drains?

Why Am I Hearing Toilet Flushing Through My Drains?

Your plumbing is a lot like your body: when something isn’t right, you’ll start experiencing symptoms that may point to the problem. However, unlike your body, symptoms of a problem with your plumbing are fairly simple and in many cases make it easy to figure out what’s wrong so you can get it fixed. One of these symptoms is a distinct and notorious gurgling noise coming from the drain in your shower or sink when you flush the toilet. The two are seemingly unrelated, so why is one impacting the other? If you experience this problem, do you need to have the issue repaired by a professional?

Here’s a brief explanation of what this sound might mean and whether or not you should be concerned.

Why the Strange Sound?

Have you ever tried to pour milk from a brand new, full gallon or tried to empty the entire contents of a two-liter bottle of soda all at once, then you probably know that if you pour too fast, the flow is not smooth, but rather choppy as the liquid struggles to escape the bottle. This is because when liquid flows out of the bottle, air can’t access the space that’s created by the liquid leaving, thus creating a vacuum. Because nature abhors a vacuum and needs to find a way to fill it, the air briefly forces the liquid to stop flowing and forces its way into the bottle, creating that glug-glug-glug effect that you’re familiar with.

This is the same principle that causes the gurgling in your drains. When you flush your toilet, air needs to be able to fill the spot vacated by water, and water needs to be able to flow into spots and replace air. When your plumbing is working in perfect condition, this is normally not a problem, leading to simple and quiet operation. This is because your plumbing system usually has a vent that allows air to easily access your pipes and fill in the spots where it needs to, essentially performing the same function as poking a hole in the top of a bottle as you drain it.

But when that hole becomes clogged, the water can no longer flow smoothly, and instead you get the familiar gurgling noise that sounds as though your plumbing is struggling.

Two Possible Causes

There are two possible causes for a blocked vent that could lead to this gurgling noise: a blocked vent pipe, or a damaged p-trap. The p-trap is a small U-bend in the drain pipe between your shower drain and the rest of the drain pipe that traps water and prevents methane gasses and other foul odors from coming back up through your drain lines and out through your shower and sink drains. The p-trap simply traps a small amount of water in the bend itself in order to prevent the odors from leaking back through. However, when the P-trap springs a leak and drains or the water trapped it dries out because of lack of use (usually for several weeks), then you’ll hear a gurgling sound when you flush your toilet.

The second possible cause is the vent in your plumbing lines clogging up and preventing air from reaching your lines when needed. Essentially, when there’s no water in your plumbing lines, air needs to be able to replace the water or else you create a vacuum. Air comes in through a plumbing vent, which is usually a pipe that extends straight up out of your roof. When the plumbing line jams, there’s only one way for air to fill your plumbing, and that’s usually through the exit to your drain line, which means the air will have to work its way up the same line the wastewater is traveling down, creating the glugging, gurgling noise.

How to Repair Each Issue

There are fairly simple ways to fix either one of these problems. The first: plunge your toilet. Using a plunger, completely cover the exit hole push down on the handle, and then quickly pull upward. Repeat this process several times in rapid succession and then flush your toilet to see if the issue has gone away. If continual plunging doesn’t get rid of the gurgling, then your issue is most likely in your vent.

Most of the time, vent clogs occur in an elbow in the line, where debris that falls in the vent can build up and needs cleared out. The easiest way to do this is with a garden hose or plumbing snake. To use a garden hose, simply bring the hose up to your roof and aim it down the vent nearest to the room where you’re hearing the gurgling noise. Then turn on the hose, let it send water down the line for a few minutes, and it should wash away the clog. If this doesn’t work, use a plumbing snake to clear out the line. Be really careful whenever going on your roof: not only do you not want to damage your roof, but you don’t want to injure yourself either.

If you’re experiencing a plumbing issue, such as a gurgling sound, don’t hesitate to contact the skilled Bartlett plumbers from Smith’s Plumbing Services! Call us at (901) 290-1110 today to request an appointment or receive an estimate.

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