Are you dealing with the maddening drip, drip, drip of leaking bathroom sink? There are several reasons why this issue might crop up. But whatever the cause may be, the end result can be water damage and even mold. It’s vital to get under the sink and get to the bottom of the issue as soon as possible. Let’s take a look at why your bathroom sink might be leaking and how you can fix the issue. 

What Causes Most Bathroom Sinks to Leak?  

There is a range of reasons why a bathroom sink might start leaking. Before you can fix the issue, it’s important to identify where the leak is coming from. Start by emptying the sink and drying everything off. Once the area is moisture-free, you can run water through the sink to see if you can find where the leak is sprouting from. 

Check the water supply, p-trap, and sink drain connection – these are the most common problem areas. Remember, leaks in any of these areas can be very small so if you don’t see the source immediately, lay paper towels around the sink drain or water supply lines to get a better idea of where it’s coming from. Check back in a few hours to see where the water is coming out. 

Another way to check for leaks if it’s not immediately obvious is to wrap toilet paper around the supply line, connections, and supply valve. It will likely reveal where the water is coming from after a few hours. 

If you still can’t seem to figure out where the water is coming from, the P-trap might be to blame. Check if this is the issue by filling the sink, opening the drain stopper, and looking for leaks in the trap as the water drains.

A corroded tailpiece or a loose drain connection could also be the culprit of a leaking sink but these issues are not as common.

How Do I Fix a Leaking Sink? 

The first step in fixing a leaking sink is the turn off the water supply. You can do this by twisting the valve located at the water supply line. If this isn’t available for any reason, you can turn off the water supply for your entire home. Be sure to allow the last of the water to empty out before starting on any repairs.

Here are some items you might need:  

  • Dry rag
  • Toilet paper
  • Adjustable wrench
  • Plumber's pipe compound
  • New supply line
  • New supply valve
  • Slip-joint pliers
  • Locking pliers

By this point, you should know where the issue is coming from…

If it’s the Water Supply

  1. Start by tightening the connections where the supply line connects using an adjustable wrench.
  2. Unscrew the nut and apply some plumber's pipe compound directly onto the threads and the washer within the fitting. Put the nut back on hand-tight. 
  3. Repeat the second step with ​​compression nut and packing nut. You might need an adjustable wrench for the packing nut.  
  4. If all of this fails, you might need to replace the supply line.

If it’s the P-trap 

  1. Tighten the compression collar with a pair of locking pliers or by hand. Be sure you don’t secure it too tightly or you could strip the threads or crack the nut. 
  2. If tightening it doesn’t work, take the whole p-trap apart and put it back together. The issue might be that the pipe going into the collar is not straight because the P-trap washer isn't fully seated.  The pipe going into the collar may also be too short.
  3. Be sure the P-trap washer has a tight connection. If the washer is damaged, cracked, or nicked, replace it with a new one.

If it’s the Sink Drain Connection 

  1. ​​Tighten the slip nuts hand-tight plus about a half-turn using slip-joint pliers. 
  2. Be sure the nut is perfectly aligned. If the sink drain doesn't line up just right with the waste outlet in the arm, the connection there might get thrown off.
  3. If you can’t seem to adjust these off-kilter connections, you may have to take apart the entire trap and install a longer pipe to straighten out the connections.

Take the Guess Work Out of Fixing a Leak

It can be a frustrating ordeal to track down a leak and fix it properly. If you’re feeling out of your depths, give our trusty team a To the T Plumbing and Heating a call! We are available 24/7 for any and all of your emergency needs. Our top-rated plumbers will rid you of your leaky sink woes in no time!