Two Oval Holes in Sink Drain Pipe

[Peggy Noland]

In our bathroom sinks, when I took the stopper out, I noticed two oval holes near the top of the drain pipe (one on either side). The holes are above the thread area for the stopper. Does anyone know what these holes are and what they are there for? Do they drain down into the drain pipe (similar to an overflow)? I have attached a photo of the oval holes. In the photo they are whitish color as they seem to have soap scum

 

[hj]

They are where the sink's overflow opening connects to the drain line.

 

[Sponsor]

 

[Peggy Noland]

They are where the sink's overflow opening connects to the drain line.

Thank you so very much! The sink has a single overflow hole in the basin itself which is what threw me off. I wasn't sure why the basin would have an overflow and then the drain itself would have another overflow. But I have read it is possible to have both.

 

[Reach4]

Thank you so very much! The sink has a single overflow hole in the basin itself which is what threw me off. I wasn't sure why the basin would have an overflow and then the drain itself would have another overflow. But I have read it is possible to have both.

Water enters the high overflow, it flows through a passage in the sink, and out of those holes below the stopper. From there down to the trap and sewer.

 

[hj]

It is not only "possible" but necessary, otherwise the water from the overflow opening could NOT flow into the drain line.

 

[Reach4]

There is a secondary purpose that is seldom noted. The overflow path can also allow air passage allowing a better flow during draining. Sinks that don't have a popup stopper, but no overflow, sometimes have trouble getting started if there is only a little water to drain.