Leaks in plumbing are common especially in older homes.
Bathroom sink leaking underneath.
The p trap is one of the most common leak problems underneath a sink but it is easy to fix.
If the leak is below a different room it could be traveling from the upstairs bathroom.
Many home plumbing problems are easy to learn how to fix yourself.
If no plumbers putty was used when installing the drain outlet flange in the sink this is another reason it may be leaking.
Clean the sink drain flange step 1.
Bathroom sink drain leaking at bottom if the drain pipe under your bathroom sink is leaking you may need to simply re tighten the nut.
Turn off water supply.
Even if the leak appears below the sink it could be coming from the toilet or tub.
Fill the sink with water and determine where your particular leak is located.