Mystery Dripping Sound

[Drips]

I can hear a ticking sound as if water is dripping in the plumbing drain in my 2nd floor bathroom. The best way to describe it is if a drop of water on the second floor is dropping all of the way down the stack to the elbow in the basement all within the inside of the pipe. The pipe in in the wall, so I can't inspect. This happens only after the water (cold or hot) runs in the sinks, which are in separate vanities separated by 8 feet. The shower, garden tub, and toilet are unaffected. It is completely random when this happens, but is slightly more frequent in the winter. I can use the sink in the morning and the sound is there, but later in the day nothing. The next day it can be the opposite or non-existent. The drip will last 5 to 60 seconds after the water is shut off.

I can trace the drains to the basement and can’t find any leaks on the ceiling of the first floor and there is no smell (mold or sewer gas). This has been going on for a few years, so if the water was outside of the drain pipes I would see some evidence in stains, smell, or dampness.

The drains are working well and are NOT slow. The house is 26 years old.

Any suggestions are welcome.

 

[Geofd]

If your not having a pipe leak,and your faucets not dripping and your water bill is normal it's possible it's residual water or condensation if you could insulate that will deaden the sound

 

[Drips]

If your not having a pipe leak,and your faucets not dripping and your water bill is normal it's possible it's residual water or condensation if you could insulate that will deaden the sound

Thanks for the reply. The pipe is in the wall, so I would need to remove the ceiling and wall sheetrock to get at it.

 

[SHEPLMBR]

It could also be the pies ticking against the studs in the wall when the water is running. Expanding and contracting. Mine do it when I run hot water.

 

[Jeff Handy]

It might just be drain water slowly being released by crud or hair at the top of the drain pipe.

Try adding an enzyme cleaner like Drain Defense once a week for a few weeks, right before bed, so it can work all night.
It gradually dissolves pipe scum that can be full of hair and soap scum.

Home Depot and all hardware stores will probably carry it.