OT Plumbing: Unvented sink attract black crud/mold?

D107

I have a fairly old sink in the upstairs bathroom that accumulates gobs of black crud in the drain and overflow slot. I ran an auger down there yesterday--sink draining slowly--and came up with hair etc. I'm quite sure there is no vent behind the sink going into the attic, only a main stack behind the toilet four feet away. But the sink waste line--below the floor cannot also be considered a vent can it? It would have to run ABOVE the sink. So a) is this a possible cause of the crud; and b) should i not install a check (cheater) vent or rather an air admittance valve under the sink? We currently don't smell sewer gases....



I'm wondering if any part of the line is galvanized, it has closed up and traps hair more readily than it would otherwise and this congestion and or lack of venting results in the crud.

GREENMAN

OT PLUMBING

THE VENT WOULD NOT CAUSE ALL THE CRUD IN THE SINK IF THE SINK IS ALL ITS MORE THAN LIKELY TO B GALVANIZE AND THAT GETS CLOG WITH TIME RUN A GOOD SNAKE TO CLEAR THE WASTE PIPE. YOU DON'T SMELL SEWER GAS BCAUSE THE TRAP UNDER THE SINK IS WORKING JUST FINE

D107

Bio-Film

Thanks Greenman. What I've read is that this is bacteria that feed off the galvanized piping. so it's not really mold, though it probably has some of that. It's too bad the previous owners didn't change over to pvc when they redid the bathroom 20 years ago. The cure is bleach/water mix, also vinegar & baking soda rinse every few weeks or so to keep it bay. and brushing it out with one of those long tubular refrigerator brushes when necessary.



Thanks again.

icesailor

Black Crud:

If the stuff you are speaking of is soft and black and is in the overflow drains holes on the pop up assembly. and is also being found stuck to the side of the drain, it is "normal" and has nothing to do with galvanized pipe or closeness to a vent.



If you pull up the pop up, and look down in to the drain, and you see the water in the top of the trap, and there is no hair hung up in the lift rod, and the water in the trap seems to have a smaller circunfrence than the top, it is soap, toothpaste and shaving creal that is sticking to the sided of the drain. Toothpaste et-al will also settle in the bottom of horizontal drains.

There are heavy duty drain cleaners out there that will clean the stuff out. Draino and Liquid Plumber aren't the ones I am talking about. Slow drains have more to do with crud build up than location of a vent. Vents do more to protect from trap seal loss than drain slowness. Though it can help with build up.

meplumber

Be Careful with some of the Industrial Type Liquids

Icesailor is correct in his diagnosis.  It sounds like soap and toothpaste residue to me as well.

One note.  Be very careful of some of the more "heavy duty" liquid drain cleaners.  If it is an old house with copper or older galvanized drainage, bad things can happen.

My suggestion is a clothes hanger.  Straighten it out and give it a run through the popup assembly once a month or so.

rlaggren

Best drain cleaner is a proper sized snake

Hope this is all past for you but I'll chime in my .02 before bed time:



For a bath basin, 1/4" x 25' is the standard. Various "heads" depending on brand etc, some work better than others. Try a "hand top" sold at most box and hardware stores first because they're cheap, easy and might work perfectly. Manually powered gizmos, look kinda like an old spinning top, only supper sized, 10" in diameter; snake is inside. You pull out a short length, twist the nob on the nose to grip the snake then push snake down the drain while holding the "top" and turning with the handle on the back; repeat until life is better.



When you hit something hard (likely a 90 degree turn in the pipe), try various in/out, back/forth, left turn/right turn stuff to persuade it around the bend. It's a real good exercise for you wrists. If it becomes just hard to turn in general, pull it back out (most likely you don't have to turn it, just pull) and see what you've caught. Then back down again.



The basin drain will likely join the toilet or the shower drain w/in 10' or so. If it joins the soil pipe, that's it, you're done. If it joins the shower drain, that's probably one reason it's running slow - hair. Run the snake to where the shower drain either goes vertically down or joins a soil pipe.



You can rent a version of this built onto a drill motor; make sure you get the 1/4" cable - the larger one is for kitchen sinks and won't go down your basin drain.



If your "tubular" (drain below the sink outside the wall, usually 1-1/2" chromed brass) is in good shape you can do all this w/out taking it apart - just run the snake down through the sink drain; remove the stopper if there is one. Else you need to take the tubular apart and snake straight into the waste tee in the wall... Or is this an S-trap the goes down through the floor? Same idea. If you gotta take it apart, you gotta take it apart.



Heavy duty drain chemicals are NOT RECOMMENDED! It sounds like the house may be fairly old. You run a real risk of burning through you pipes if you use the heavy duty acid drain cleaners - besides staining your plumbing fixtures and floor and maybe scarring yourself big time if any touches your skin anywhere. The stuff shreds 4 layers of heavy canvas in about 60 seconds; I was lucky I had chemical resistant boots on under. Don't go there.



Rufus