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6 Steps on How to Fix a Leak Under the Sink


Sink leaks are common in almost every household. To attest to this fact, most households have a plumber’s contacts saved on their phones or posted conspicuously at a strategic place in their homes. Going by the frequency of leaks, knowing how to fix a leak under the sink can save you a lot of stress.

Before you can fix a leak under the sink, you need to know the different parts of a sink. First, there is the sink, also known as the washbowl. This is where water pours into from your faucet. The faucet is simply where water pours out from on its way to your sink or washbowl. It is known commonly as a water tap.

Next is the drain outlet flange, a metal disk at the bottom of your sink with holes punched into it. It looks like a strainer, or rather, a sieve. Then there is the drainpipe, which, as the name suggests, drains out the water.

Here is a six-step checklist to help you fix a leak under the sink.

1. Check If the Drain Pipe under the Bathroom Sink Is Cracked

If the drainpipe is the source of the sink leak, the cause of the leak is in most cases a cracked drainpipe. You can fix this by just applying plumber putty where the crack is to prevent further leaks.

Use plumber putty to make watertight seals around a drain or a faucet. It is a flexible and dense substance you can apply on a drain or faucet, even if the sink is not leaking; just as a safety measure. As the saying goes, ‘prevention is better than cure’.

2. Check If the Rubber Sealing Washer Is Too Tight

A rubber-sealing washer or a gasket goes between the sink and the nut. It is used to prevent leaks. For a gasket or a rubber-sealing washer to do its job well, it has to be completely flat.

When a gasket or a rubber-sealing washer is too tight, it gets overstretched. As a result, it does not completely cover the area it is supposed to cover. This could end up causing the leak. The rubber-sealing washer could also be too small for your sink. For a rubber-sealing washer to prevent leaks, always get the right fit or size.

3. Check If the Drain Pipe Is Properly Aligned To the Washbowl

You might have hit the drainpipe with enough impact to cause it to move out of place. If the drainpipe is not aligned to the washbowl or is off the centre of your sink, it is impossible to achieve a tight seal.

When the drainpipe is misaligned with the center of your sinkhole, you are bound to have some open spaces from where water can escape, causing leaks under your sink. The solution is to perfectly align the drainpipe with the sinkhole. This simple manoeuvre will usually stop the leak unless you have another problem.

4. Check If the Nut Is Loose

If the nut is not tight enough, water will simply drip through it. The simplest and probably the only way you can check if it is tight enough is by checking whether it can be tightened further. If it can, go ahead and tighten it. This is an easy thing to do as long as you have the right tools.

Tightening a loose nut is perhaps the simplest plumbing task you will have to deal with. If this is the cause of your under sink leak, the problem will be solved as soon as the loose nut is tightened.

5. Check If Plumbers Tape Was Used

A plumbers tape is usually placed between the threads on the nut and the drainpipe. It helps make the system watertight. If a plumbers tape was not used, water could end up seeping through the threads of the nuts under your sink. Therefore, if you discover plumbers tape was not used when installing the system, adding it might just solve your problem.

6. Check If the Nut Is Cracked/ Damaged

Liquids have the ability to take any shape depending on the space they occupy. This means if a nut is cracked or damaged, water will find its way through the spaces caused by the damage. The only way to remedy a damaged nut is to replace it with a new one. If a nut is damaged, go to your nearest hardware store and buy a replacement, but make sure you get the right size. Remember to carry the damaged one to make sure the replacement is of exact dimensions as the one being replaced.

A leak under the sink can flood your entire house. However, if you follow the above checklist, you can identify the cause and fix the leak under the sink before the issue gets out of hand. This could be all you need to do before the plumber arrives to inspect your entire plumbing system for potential faults.