Pipe Leaking Under Bathroom Sink: Here’s What To Do

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You will need to check the drainpipe underneath and make the nut in it tight. If this does not work, remove all the parts there, including the P-trap and the drain. Then wrap the drain using a plumbers tape or add a plumber’s putty between then reassemble the pieces back.

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Why Is My Bathroom Sink Leaking Underneath?

Leakages in the bathroom sink can irritate, especially when they make everything in the cabinet underneath wet. Also, they may create a pod of water which may make one slip and fall. While it is common to have bathroom sink leaks, people need to know how to avoid them.

One way you can prevent bathroom sink leakage is by finding out the cause of them. There are many reasons why the bathroom sink leaks underneath and among the top cause is issues with the drain pipe. When you determin where the leak is comig from, fixing it should be easy.

Among the common issues that the drain pipes have that can lead to leakage is it being loose. If the bathroom sink is leaking, ensure that you first check the nature of the drain pipe. Is it tight as it should be, or it’s slightly loose?

If it is loose, check the part where water may pass through to fix the issue. Usually, the point of it being open mainly emanates from the nut that connects the drain pipes. If the nut is not as tight as it should be, it allows water to pass through it.

Leakages also occur when there is some disconnection in the supply lines. If the supply lines are the issue, then you will notice that water will be pouring out with so much pressure from a certain point.

Bathroom sink leakages occur because of poor installation of the fixtures that allow water to pass through. There will often be a need to use the plumber’s putty when installing certain features, such as the drain outlet flange.

If you fail to use the plumber’s putty when installing this feature, then it will probably leak afterward since it will not be intact enough.

The basket strainer present in your sink may also lead to leaks. Such leaks occur mainly because of a loose ring nut that is usually present underneath the sink. It is always important to ensure that you make this nut tight and if it continues to leak, use the plumber’s putty to seal the part.

You may also need to check whether there are cracks on the drains and pipes or the plastic and metal threads have stripes. Anytime there is damage in the gasket or drain pipe, drain outlet, the rubber sealing, or the nut has cracks or general wear, there will be leakage. Therefore, it is always important to inspect such parts from time to time and fix them before the problem escalates.

Also, you need to ensure that you regularly inspect the P-Trap. The P-trap is usually the curved part that is present under your bathroom sink, and it serves to prevent the foul smell from coming through your drains.

It may be hard to realize that your bathroom sink has a P-trap, and for this reason, identifying a leak from it may be hard. Usually, debris, dirt, and other small particles normally collect around this part. They eventually block the piece; therefore, draining water will be an issue that results in leakages.

Also, when the debris collects around the p-trap, it may bring about corrosion, especially if there are metal parts around your sink. Such also leads to leakages, and the only best way to fix the issue is by replacing the P-trap.

What Causes Pipes to Leak under the Sink?

If there are leakages underneath your bathroom sink, one of the most common places that you should inspect is the pipes around it.

Many reasons may make the pipes leak under the sink. Water leaking under the sink may leave a long-term issue within your home, including mold growth and unwanted smells.

Use a rubber sealant to ensure that the water pathway is airtight. It is common to have a broken seal along your pipes which will in turn cause leaks. Usually, when dealing with plastic pipes, you will need to use some rubber sealant on certain connections, but you may not need much if you are using a metal pipe.

If you have had the pipe and the sink for a long time, then its quality degrades with time. The rubber sealant on a certain area along the lines will also degrade with time, and this may cause cracks or it breaking apart. The breaking is now what causes the leakages.

Moreover, clogging along the water lines may also result in the pipe leaking. Such happens when maybe there is debris or particles that accumulate along the water passages, therefore preventing water from passing through.

Usually, the trash causes a build-up in pressure that may lead to overflowing, which causes the pipes to burst.

When installing water pipes, they need to be so that the water will be flowing against the gravity, and if the pipe laying is not correct, they may burst. Also, pipes may leak if their installation and layering are not proper.

Therefore, it is important to ensure that you engage a professional to do the tube laying for you and make other connections within the sink since they are well versed with such a procedure.

Well, you may have the laying of your pipes correct but is the pressure in them okay? Some high water pressure is usually the best feeling when having a shower, but you may not realize that the water may be hitting your pipes hard from the inside.

If the pressure keeps on getting high, then there is a high chance it will cause leaks in your pipes.

You, therefore, need to ensure that water is running through your pipes under the correct pressure, which in most lines is usually about 60 psi. Otherwise, it may cause the pipes to burst. You can engage with your plumber to regulate the water pressure for you.

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What To Do If the Pipe under the Sink is Leaking?

You need first to ensure that you identify the part of the pipe where the leak is emanating from to know how to fix the issue. The most common areas for leaks include the shut-off valves, pressurized water hose pipes, and drain pipes.

Usually, tubing links the sink to the water supply, and these tubes normally connect to a valve. If the Shut-off valve is not tight enough, it leads to leakages, so the best thing to do in such a case is to tighten it. Ensure that you make the nut on the valves tight, and if this does not stop the leakage, you only need to replace the valve.

If the leak is emanating from the drain, do some procedures to ensure it is okay. You should start by inspecting the part of the drain that has the leaks, and to do this, run water through the sink, then check each piece that connects the sink to the wall.

You can use a tissue when inspecting such that if it gets wet, you know that that is the part with the leak.

Now, how you fix it will depend on the problem you diagnose. For instance, if the issue is on a slip joint, all you have to do is ensure that the alignment along the pipes is correct and tight.

If this does not fix the issues, you may need to apply some plumber putty on the part, and you should do the same if the problem is on the washer or the basket strainer.


Pipe leakages can be messy, and for this reason, it is always important to do proper inspections from the word go. You need to ensure that the pipe installation is correct and regular checks along the drains to identify some cracks.

You can also easily fix pipe leakage problems by making the nuts tight and using a plumber’s putty or calling a professional plumber to help you check the problem.