A leaky bathroom sink drain can lead to major problems if not corrected. Sure, a bucket under the sink can temporarily solve the problem of ruining the items you have stored, but letting this go can create mold and mildew growth. A leak will also get worse, and end up damaging the the drain further. This can lead to much more costly repairs. Repairing a leaky drain is generally easy and straightforward, requiring only a few tools and less than an hour of time.
Step 1: Shut Off the Water Supply
Anytime you are working with plumbing, you should cut the water off. For a bathroom sink, you can just use the shut off valves that are found under the sink itself. After the water is off, open the water line by turning both the hot and cold water on. This will allow any water in the pipes to drain out, preventing a watery mess later.
Step 2: Check the Joints
A sink drain tends to leak around the joints. You can usually feel water building up around the area on the joint that is leaking. You might need to crawl under the cabinet with a flashlight to find a leak. There are joints where the pipes connect with each other, so you should only have a few joints to check out. You can tighten the joints by hand, and use a wrench to secure it. You don't want to over tighten or you can actually make the joint looser, causing it to leak more. Once the joints are tightened, you can turn the water back on and test to see if the leak is corrected. If it is, you're done. If not, move on to the next step.
Step 3: Replace Washers
If the above step didn't work, turn the water back off at the shut off valve. Remove the joints from the pipes and check the rubber washers. The washers are used to help secure the pipes together. With time and use, thees can wear down, become brittle and crack. This causes leaking. Simple replace the rubber washers, reconnect the joints to the pipes, and test it again. If it still leaks, go on to the next step with the water cut off again.
Step 4: Inspect for Rust
A rusted pipe can leak around the drain as well. Rust will eat at the pipe and cause small holes and cracks that water can easily get through. Take your flashlight and inspect the pipes under the bathroom sink for signs of rust. If you see rust, remove the pipe and take it to a home improvement store to purchase a new one. Replace the rubber washer, and place the new segment of pipe in place. Tighten the joint, and test the drain again.
Step 5: Temporary Solutions
If the above steps haven't stopped the drain from leaking, use some plumbers putty around the area where you see the water coming from. This isn't meant to fix the problem, but will give you a temporary seal until you can get a professional to correct the problem.