Clogged Kitchen Drain From Hades

criticalmass048January 10, 2009

My friend recently bought a house, and the kitchen sink acts up. After running the water for about 2 minutes at full strength, it began backing up. When I say "back up", I mean so bad that it takes 5 minutes just for the water to leave the sink. She's tried plungers, drain cleaners, you name it. No other drains act up, just that one.

Thinking it might be the garbage disposal, I took it off, and checked it out, but it looked fine. I also cleaned some gook out of the S-trap.

So rather than re-attach the pipes, since I had easy access to the drain, I took the water line off the faucet, put it right into the drain pipe, and turned on the water pressure. Sure enough, it ran for about 30 seconds before clogging. Five minutes later, with a flashlight, I could still see the water level; it had only dropped about 8 inches.

I went and got my 25' auger. After 8 attempts, I did clean some gook, but it still not unclogging!

Underneath the sink in the cellar is a 90deg elbow, 18" of 1.5" diameter copper pipe, followed by a 45 degree elbow, followed by 6' of the same pipe, which then goes into the main waste line. The 6' segment is soldered at both ends.

While I am familiar with basic soldering of pipes, I'd like to know if I can just remove the 6' section, and what I'm getting into here. Can I handle this, or is this a job for a pro? Any ideas what this could be?

Thanks in advance!

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It sounds like it could be a venting problem. Is there a vent from behind the trap leading up through the roof? If not, and you're able to snake all the way to the main waste line, that's most likely where the problem lies. If there is a vent, then it may be clogged. Try running your snake down the vent pipe from the roof.

Beyond that, what kind of disposer is in place? If it's a small economy model or very old, it may not be grinding very thoroughly. Years ago I lived in a place with a cheapo Insinkerator Badger disposer. It seemed to work just fine, but I was constantly plagued with a clogged drain line. I finally replaced the old, cheap disposer with a 1 HP top-of-the-line Insinkerator. The more powerful units have much better grind elements, spin at a much higher rpm, and grind food into much smaller particles. After the replacement, I never had a stoppage problem again.

Since that time, I've become a landlord. When I've had recurring problems with clogged kitchen drain lines, I change out whatever disposer is in place with a 1 HP model. After that, I seldom have problems again. IMO, spending more for a good disposer saves money. Roto-Rooter is expensive.

    Bookmark   January 11, 2009 at 1:00AM
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No, there's no vent line, and I can go directly from the sink to the main waste line. Since all the other drains in the house are fine, one can only assume that the clog is NOT in the main waste line, but at the beginning of the branch leading to the sink, correct? And is it safe, legal, or even possible for a layman to disconnect that? I think soldering the one end (with the copper elbow joint) would be easy enough, but then I would have the other end, which it the cast iron main drain line.

    Bookmark   January 11, 2009 at 10:15AM
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sounds as if you have 2 or 3 different types of pipping materials, and no need a pro to come out and
starting at the main, replace the pipping and install a
drain system that will work..

    Bookmark   January 11, 2009 at 2:52PM
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If you can snake all the way to the main waste line, you probably don't have a blockage. The problem has to do with the unvented drain line. Drains can stop flowing if there's no place for air displaced by water in the drain line to escape. Even if weren't having a drainage problem, without a proper vent, you run the risk of the trap being siphoned dry.

I'd say you need a plumber to resolve the vent issue.

    Bookmark   January 11, 2009 at 3:27PM
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I understand what you are saying about the venting. It's the same concept as to why soda comes out of a bottle "glug glug glug" -- as liquid moves out, air moves in. I get that.

What I DON'T get is all the other drains are fine (there's a bathtub on the same floor), and how much water could it POSSIBLY take to "block up" 8'L x 1.5"W pipe!?! That just doesn't make sense to me. The neck on a bottle of soda is tiny compared to a 1.5" diameter pipe. SURELY there's plenty of room for air to come in!

Here's a thought: Perhaps the drain pipe is not at a proper angle to drain. Could that do it?

    Bookmark   January 11, 2009 at 5:44PM
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Is your sink a double?

    Bookmark   January 11, 2009 at 7:16PM
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No, it's a single

    Bookmark   January 11, 2009 at 7:58PM
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Unless the line is really greasy & foul smelling, I'd still snake it again. What do you mean by "8 attempts" at snaking? Do you mean that it took 8 attempts to feed it in there once? If so, then try again. As you feed the snake, turn it slowly while adding moderate pressure.

If it IS greasy/gunky/foul smelling, then I'd try a chemical drain opener, but only after the line has had a chance to drain. (think how you'll pour it in there, too - might be tricky)

As far as cutting the line, I'm sure you could probably do it (once other remedies are exausted), and provided you plan what's next. You can reconnect the piece with banded fernco couplings or you can replace the piece with PVC, if you like.) (Don't do this if there's chemical still in the line.)

Start with snaking again - hopefully that will clear it.

    Bookmark   January 11, 2009 at 9:05PM
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Try the plunger again. For double sinks use two plungers at the same time. Run water until it backs up in the sink, leave water running and place plunger over the drain. Water in the sink is desirable when plunging. It helps seal the plunger to the sink. Believe it or not, the plunger acts most effectively by sucking back when it is lifted. It loosens packed debris. Plunge vigorously several times. The sink water helps wash out loosened debris. About the vent. Possibly the vent exists but has not been recognized/identified. If no vent, get one installed. By a pro.

    Bookmark   January 11, 2009 at 9:08PM
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Is the bathtub drain vented or near the main vent stack? That may be why it doesn't have any problems. Every drain in a waste water system needs to be vented. The symptoms you described in your original post are classic for a venting problem.

I'm not a plumber, but as I understand it, water running at full strength can overwhelm the drain. when that happens air can't escape from the drain line and a bubble builds up in the drain pipe. The bubble tries to rise up through the pipe, but increasing pressure from water building up in the drain and sink won't let it clear and may even push it back down the line.

The bubble has no place to go for escape, except through the drain opening, but the pressure created by water passing through the drain and into the pipe is pushing down on the bubble, keeping it in place. Even after the flow of water into the sink stops, the weight of the backed up water is bearing down on the trapped air bubble. Until enough water can trickle past the bubble to lighten the load holding it in place....the drain is stopped up. Once the pressure from trapped water lessons enough for the bubble to push past it and escape (it's sort of like a burp), the drain will flow freely.

A properly vented drain won't have this problem. The displaced air will be able to escape through the vent line which won't have any oncoming water or pressure in it to impede its escape.

Here is a link that might be useful: Wikipedia - Plumbing Vents

    Bookmark   January 11, 2009 at 9:44PM
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Sorry it took so long to get back to everyone!

-- What do you mean by "8 attempts" at snaking? Do you mean that it took 8 attempts to feed it in there once?

I mean I fed the snake a few times, and got some minor "gook" out. I then withdrew and reinserted it about 5 more times, felt it hit something solid (approximately the right length to be hitting the main vertical drainage pipe), twisted it around, withdrew it, and found nothing stuck to the end. I did it again a few minutes ago, and it came out clean again.

-- Try the plunger again.
Plungering for a few minutes will free it up, but it always seems to clog again

-- Is the bathtub drain vented or near the main vent stack?
It's very difficult to tell, since the other drains are practically up against the floor above me, but it doesn't appear so. If it is, I can't see it.

-- Possibly the vent exists but has not been recognized/identified.
I just still can't get over the fact that the other drains would be connected to this vent, but the kitchen sink wouldn't, considering the drain pipe terminates within inches of all the other pipes. Logic would suggest that there is no vent, so therefore why is there no other problem, such as with the bathtub drain, which is on the same floor and within 15 feet? Draining a bathtub would overwhelm the drain a heck of a lot faster than the kitchen sink, wouldn't it?

    Bookmark   January 16, 2009 at 9:40PM
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Each drain requires a vent. The main waste line also must be vented. Very often, particularly in older houses, the main vent is straight up from the only toilet in the house. Because the bathtub is immediately adjacent to the toilet, it sometimes is vented into the main vent stack. The same is true of a lavatory sink, often located on the other side of the toilet from the bathtub.

A kitchen sink, on the other hand, is very often some distance (more than a few feet) from the main vent stack. Because of that, it requires a separate vent to ensure that it remains free flowing if the drain in the sink is overwhelmed. It makes no difference if the drain pipe terminates within inches of the other drain pipes. If air pressure can't equalize in the pipe, it's not going to drain properly.

Since you don't seem to understand the purpose of proper drain venting, I suggest you read the "Purpose" section of the Wikipedia article at the link below. If you're still not convinced that you have a venting problem, call a plumber. Perhaps he or she can explain your problem by pointing out the apparent inadequacies of the existing waste water system.

Here is a link that might be useful: Wikipedia: Plumbing Drainage Venting

    Bookmark   January 17, 2009 at 1:00AM
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Ok, I've read the article, and I agree, it really MUST be a venting problem. I really don't mean to questioning your knowledge or experience. After all, I came here because people know what they're talking about, right?

My friend called the previous owners of the house (friends of her father who retired and moved to Florida). They only owned the home for six years, and said they never really had a problem with it until recently, maybe six months before they sold. They would just plunger it and leave it alone.

So being that it looks like this house was built in the '50s or '60s, and apparently does not have a vent, I'm left with:

a) Why doesn't it?
b) What would cause it to operate fine for at least 5 years without a problem, and then act up suddenly?

I'm going to take another look at it today and see if I can find a vent -- any vent at all. I found the main sewage pipe, obviously, but there was no vent next to it. I'll bring my camera and take pictures, in case they'll be of any help.

    Bookmark   January 17, 2009 at 11:10AM
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