Mold growing in drain vent pipe causing odors

[UltraP]

I noticed unpleasant odors emanating from my bathroom sink. Opened the cabinet below and was treated to a disgusting sight of a moldy clear plastic tube which I assume is the drain vent - see picture attached.

I checked my 3 other sinks on the house and none of them have this drain vent and none of them have the odors.

My home is new construction (6 months). Built by CastleRock in central Texas. Before I go to the builder I'm trying to understand if this is even properly installed, why it gets so moldy and why the vent is only installed on 1 of 4 sinks in the house?? (In master bath, 2nd sink).

I appreciate any insight you may have.

 

[Rickyman]

That’s a condensation drain for your air conditioner/furnace. We use black 7/8 dishwasher hose.

 

[Mr_David]

The foul odor is more likely from the tooth past residue that clings to the pop-up assembly. Try running a little or a lot of extra hot water after you brush your teeth.

I have first hand experience.
less than a month or 2 after I installed an new sink it started to smell bad..
3 people were using that sink, one of them my grandson.
They would not or barely rinse the sink out after they spit that foamy concoction out. I can see the dried film in the sink.

Since the grandson and his dad moved out and the sink gets properly rinsed, it does not stink anymore.

I have cleaned a lot of sink drains and you can tell who runs water and who does not.

Clean AC drain:
Go find you AC unit in closet or attic. pour a diluted mixture of bleach and water down condensate drain.

Clean sink drain. Remove pop-up plug and see if you have any slim build up.
Lots of hot water and maybe a bottle brush.
Fill the sink to over flow with a little bleach and let the bleach flow into over flow.

 

[UltraP]

Thank you Mr_David for the detailed response and tips! I will thoroughly clean everything with bleach.

Also thanks to Rickman for the quick reply.