Expert: Sharon McCarthy - 6/27/2009

Question
QUESTION: My bath room sink does not drain sometimes it will drain slowly for a couple of days, but then it stops and I have to scoop the water out of the sink to empty it.  I have PVC plumbing.  I have used liquid plumber, baking soda and vinegar, and several other products to no avail. I have also taken the drain apart (it was clean) and snaked the drain where it enters the wall (it also was clear). The sink in this bathroom always drained slowly but it always emptied within 10 minutes or so.  However, I replaced the sink while remodeling a year or so ago and the draining issue got worse.  I noticed that the sink does not have a vent and was wondering if this could be the problem.  If this is the cause of my drain stopping is there any way to fix the sink without replacing it.  Thanks for your time.

ANSWER: Dear Angelique,

 First you need to determine where this blockage is, then you can go about solving it. You said you took "the drain apart" and it was clean. Did you mean you took the trap off? and the trap was clean, and then you snaked where it enters the wall, and that was clear?

 OK, here's my suggestion. Get a small bucket or deep bowl and place it under the "P" trap. Remove the trap. Now run some water into the sink and see if the water flows freely down into the bucket. If it appears the water runs very slowly, then there is some gunk in the pipe somewhere between the sink flange and the trap.

  This is the most common problem in lav sinks. Crud collecting on the pop-up or the lever down below that lifts the pop-up. I'm not sure this is your problem since you said you replaced the sink a year or so ago.

 This experiment should at least tell you that the problem is or isn't right up front. If the water seems to run OK down to the trap, and the trap is clean, and the pipe going into the wall is clean, then your problem is further down the line.

  Liquid plumber usually doesn't work if a blockage is further down the line. The line may be full of water for 10 or 15 feet. By the time the chemical gets to the blockage, it's too diluted to do any good. If you find that you have a blockage down the line, you may have to either call a plumber who has a small electric rooter, or rent one and do it yourself.

  I doubt very much that the lack of a vent in the bowl is causing this. Let me know what you find out, OK? sharon

---------- FOLLOW-UP ----------

QUESTION: The tarp was clean, and when we snaked where it enters the wall and it was clear.  When the trap is off water runs freely into the bucket.  I took the sink stopper/pop-up and lever off when the sink first stopped draining and have not put it back on.  I guess that this means the problem is further down the line, but every other drain in the house works perfectly.  This sink is the last drain in line on the way out of the house to our septic tank(about 15-20 feet from the house and which was pumped out about 6 months ago and is working fine). Thank you for your time and help.  I guess we have to look for a blockage further down the line.

ANSWER: Angelique,

  All small drains, like sinks, tubs, showers, laundry, are teed into the big pipes coming out of the toilets, usually not too far away. Visualize a tree going backwards; small branches go into big branches which go into limbs which all finally end up at the trunk of the tree. The "trunk of the tree" would be the main line going out to the septic tank.

  A lot of crud goes down bathroom sinks. We think we're not putting anything down, but over years a collection of toothpaste, face cream, shaving soap, a few hairs starts building up on the inside walls of the pipes. Often this will come loose here and there, and catch in a bend in the pipe before it enters the main pipe.

  Question, was there some specific reason you had your septic tank pumped? Is your house pretty old? Was sewage backing up and that's why you had the tank pumped? Or are you on a regular schedule?

  I've been plumbing for 26 years, and I'd say 2/3 of the residents in my area are on septic systems. Rarely does anyone really need their tank pumped. I encourage people to add bacteria regularly to keep the breakdown of solids active, and this usually keeps the tanks clean.

  Pumping services will tell people that their tanks should be pumped every 4, 5 or 6 years. In my opinion this is BS. They are in that business, and they are creating work for themselves by saying this.

  I'd say in 90% of cases when sewage begins running slowly or backs up, the problem is in the line going out [a blockage, often roots], or at the tank opening where debris or roots can collect and impede water from entering the tank [which can be loosened by opening the plug on top and sticking a pipe down, or pulling out the roots].

  Along with this 90%, but less often, there may be a blockage from the tank to the leach field, usually roots. In very few cases is the problem IN the tank. Just thought I'd mention this. These pumping services make a lot of money off people who don't know better. This is a big pet peeve of mine. Good luck with your repair. sharon

---------- FOLLOW-UP ----------

QUESTION: We had the tank pumped because sewage was backing up into the downsatris bathroom (not the same bathroom that the sink does not work in) and our plumber said that we needed to have the septic tank checked.  When they pulled off the lid it was completely full, so we had them pump it which fixed the problem.  The house is 30-40 years old, and the tank had not been pumped in around 15 years; we are not on a set schedule, and put Rid-X down it monthly.  Thanks again for your help.

Answer
Dear Angelique,

  Just want to caution you. I wrote last time about the most common reasons for a sewage back-up. If your tank was full when they pulled the lid off, it may be because the water wasn't draining into the leach field. The tank doesn't neccessarily fill up because it hasn't been pumped in a long time. Most often it fills up because it can't drain out.

  Granted, after a lot of years, some of the solids that are broken down by the bacteria settle to the bottom of the tank and begin limiting the volume of the tank. In some cases, if a lot of solids are floating, they can block the flow of water out the back. Usually this occurs because bacteria hasn't been replenished over the years. But most of the time, if the tank overfills, the problem is usually a blockage from the tank to the field.

  Every septic tank has three access holes on top. A concrete plug at the front, that gives you access to the pipe that enters the tank, a large square cover in the center that can be lifted to clean out the tank, and a concrete plug at the rear [just like the one in front] that gives you access to the pipe going OUT of the tank.

  My little house is on a septic system. About two months ago, my toilet backed up. In our dry climate, roots are often the problem. I've had back-ups before. Previously the cause of this was roots growing in where the pipe enters the tank. When this happened, I'd pull the plug off, reach down and remove the roots. I had to do this about every two years. The roots always come back.

  This time, when I opened the plug, there were no roots there. And this time, the water was over the entry pipe. The tank was overfilled. I then pulled off the plug at the rear of the tank. No roots there, but the water was not draining out. I used my big rooter machine and ran the cable out towards the leach field.

  I ran about 30 feet of cable in and hit roots. When I pulled the roots out, the water in the tank dropped about a foot in a matter of minutes. My tank is over 30 years old and has never been pumped.

  I'm only telling you this for future reference. When the pumper emptied your tank, it probably removed something like 750 gallons or more. If your problem is, in fact, in the pipe going to the field, as mine was, your tank may fill up again and you'll have the same problem. If this happens, at least you'll know why next time!  sharon