I have continuing, loud, "blub, blub" noise coming from bathroom sink on first floor of house. The bathroom is one that is rarely used, but whether sink has been used, the loud noise is almost constant. The grandchildren will not stay in guest room, near problem bathroom, as the noise scares them. How can I stop the noise?

You will have to be a little more descriptive about the sound. The noise you hear is coming from the lavatory trap. However a bubble indicates back pressure caused by a partial blockage and a gurgle points to a blocked vent Can you tell me which sound it is? Also, have you ran water in the lavatory to keep the trap filled? Regards, Tom

You will have to be a little more descriptive about the sound. The noise you hear is coming from the lavatory trap. However a bubble indicates back pressure caused by a partial blockage and a gurgle points to a blocked vent Can you tell me which sound it is? Also, have you ran water in the lavatory to keep the trap filled? regards, Tom
The noise is more like a very loud bubbling sound-- not a gurgling sound. Realizing the sink is not used very often (it is in back part of house, next to spare rooms), I have tried repeatedly to stop the noise by running large amounts of water down the drain, but the noise remains, with or without use. What can be done?

Is there a AC condensate drain connected to the lavatory somewhere around the trap?