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  #1   IP: 71.112.13.71
Old August 15th, 2009, 08:34 PM
TitaniumVT TitaniumVT is offline
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Default Can ONE slow drain be indicative of a septic system problem?

My kitchen sink has started draining really sl-o-o-o-w-l-y. All of the other sinks, showers, tubs, etc. are draining fine. There are no smells, backup, etc. now or before this problem started.

I'm baffled about why the kitchen sink is draining so slowly - the p-trap is clean. I also put a 9 foot plumbing snake all the way in the drain and didn't find any obstructions. I'll keep troubleshooting the sink plumbing, but wanted to ask if ONE slow draining sink might be indicative of a septic system problem?

I would have guessed logically that if there was a problem with the septic, ALL of the drains would be running slow.

Thanks in advance for any insight!

Last edited by TitaniumVT : August 15th, 2009 at 08:37 PM.
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  #2   IP: 76.22.81.239
Old August 15th, 2009, 10:37 PM
suemarkp suemarkp is offline
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Generally, all drains will be slow if you have a septic problem. However, the closest drain to the main pipe exit will slow first, as will the one with the shortest length to the main output pipe. Those other drains could just be filling up the main pipe and their branches, and until it fills you don't have a slow drain. But if you've done gallons and gallons of water (e.g. a shower) and it doesn't drain slow or backup, then you main line and septic are probably ok.

So I'd focus on the kitchen drain. In addition to a drain being clogged, you could have a clogged vent (bird or squirrel nest, someone put something down it like a ball, etc). Is this a dual drain, so the second drain can help vent the first?
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  #3   IP: 71.112.9.64
Old August 16th, 2009, 09:48 AM
TitaniumVT TitaniumVT is offline
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Mark, thank you so much for the great reply, as always.

The laundry room is closer to the septic tank than the kitchen is by about 15 to 20 feet, and the laundry sink seems to be draining fine. I'm not sure which room/fixture would have the shortest pipe to the main line (I'm guessing it would be the laundry room given its proximity to the tank and where I believe the main waste line comes out of the house.

My tenants have taken several showers and nothing seems to be backing up, so I'm hopeful it's more indicative of a venting or kitchen drain clog problem than a septic issue. I'll check the venting today, both getting up on the roof to check the kitchen vent, and also changing the in-line vent valve under the kitchen sink. I'm also going to get a longer 25' power auger to see if there's an obstruction in the pipe further than I was able to get with the 9' snake.

In doing some research last night, I read that a good way to clear the roof vent would be to force a garden hose down it (water off) as far as it will go. Are there better techniques? Do you think there would be any issue with turning on the water down the vent to knock anything loose with water pressure? Any risk that it'll do more harm than good, or that the water in the vent won't have anywhere to go?

In response to your question: Is this a dual drain, so the second drain can help vent the first?

I'm not sure, but I think the answer's no. It's a dual sink with a T pipe connecting the two drains to one P trap. The p-trap connects to a short arm that in-turn connects to a pipe that goes straight into the floor and out under the house (it's a manufactured home). The pipe that leads into the floor has a short vent stack that extends above the trap arm and stops a few inches below the sink (that's where I'm planning to see if I can change the in-line vent valve).

Last edited by TitaniumVT : August 16th, 2009 at 10:17 AM.
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  #4   IP: 71.112.9.64
Old August 16th, 2009, 10:26 AM
TitaniumVT TitaniumVT is offline
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Mark, could you explain this part to me (the two parts of the statement seem to be saying the same thing, but that's no doubt because I'm reading it wrong)

Quote:
Originally Posted by suemarkp View Post
...the closest drain to the main pipe exit will slow first, as will the one with the shortest length to the main output pipe.
The closest drain to the main pipe exit in my case must be the one the laundry room, since it's closest to where the pipe comes out of the house and goes to the septic tank.

"The one with the shortest length to the main output pipe..." Does that mean the laundry room drain again, or do you mean whichever fixture has the shortest branch line to the main pipe, irrespective of where that fixture is in the house?
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Old August 16th, 2009, 12:19 PM
suemarkp suemarkp is offline
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I couldn't find good words to describe what I was thinking. Basically, the first branch off the main sewer line will be the lowest and first to fill if the septic is clogged. But if it goes 20 or 30' and/or upstairs, that is a lot of pipe to fill before you notice it is clogged. Likewise, if a drain a few branches in is real short and goes to a shower just above it, then that may be the first to back up because the pipe volume is so low.

If your first branch is a clothes washing machine, those dump a huge amount of water. If that drains fine, then your main line and septic are probably fine. Otherwise, that washing machine would most likely be backing up into first floor bath tubs and showers. That's how I knew my main line from the house to septic was broken -- nasty looking water coming up in the bath tub when washing machine went on spin cycle.

The dual drain kitchen sounds like what you have. In mine, when you put a drain plug in one of the two sinks, the other drains slower because the vent pipe is rather small. My kitchen drains quickest when both sink drains are not stoppered.
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  #6   IP: 71.112.12.101
Old August 16th, 2009, 05:34 PM
TitaniumVT TitaniumVT is offline
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Thanks for explaining that, Mark. It makes sense.

The great news is that I managed to fix the drain! I got up on the roof to check the vent line for the kitchen, only to discover there was none. Sigh, one of the many quirky things about manufactured homes I guess. In case it's helpful to anyone else, here's how I fixed it:

There's an inline vent under the kitchen sink. I changed the valve (a $3 repair), but it didn't seem to do much. So then I used a 25 foot drain auger attached to the end of my drill, and ran it on high several times, moving the auger back and forth to loosen up crud. There wasn't much debris coming out on the auger, so I wasn't sure if it was doing much good. The sink drained a little better, but it was still pretty slow.

Then I brought a couple of large pots of water to a rolling boil, and poured the water into the sink. As the very last bit of the second pot was draining, there was a sudden "glug glug" and the water started draining properly again! It was like something burst loose. For good measure, I boiled another pot of water and poured it down the drain - it went down really fast. Then as a final cleaning step, I poured a bottle of vinegar down the drain and let it sit for a while.

My guess is that the drain was partially clogged with cooking grease. The auger probably loosened it up pretty well, and then the boiling water liquified enough of it to break the clog loose. The vinegar should do a bit more to clean the drain of grease, but even without it, it seems to be working better than ever.

Thanks very much for the help!

Last edited by TitaniumVT : August 16th, 2009 at 05:43 PM.
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