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Backed Up main drain

2071 Views 4 Replies 3 Participants Last post by  tylernt
So my main drain backs up, at least when I run the clothes washer. Whenever the washer drains it backs up into the bathtub. Ok easy enough right, so I go through the process of trying to snake the drain for the tub, nothing comes of it. I go into the crawlspace and notice a P-trap on the main line right beofre it enters the stack (so the P-trap is up stream of the stack) I assume, and you know what that spells, that the P-trap must be easy enough right, i cut out the P-trap and put in a new one, but before I do that I run my snake back to the stack, no clogs found, and the P-trap is not clogged either. However, after replacing the trap the drain doesn't back up as bad. The toilet never backs up either and I never found a clog up stream of the stack. So i'm confused. I half wonder if the vent may be clogged and when I cut the p-trap out that extra moment of releasing the pressure is what has made the drain not back up as bad. I checked the vent pipe at the top of the roof and can't see anything blocking it, but I suppose its possible there is a clog in it lower down. I have not snaked the main line from the stack back to the sewer, but if that was clogged wouldn't my toilet be backing up too? I just don't know, I'm a sparky, plumbing is not my area of expertise but I am plenty mechanically inclined so I'd like to fix the problem without having to call a plumber. Thanks all!
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When you have one fixture backing up into another, the clog is downstream of both of them. I'd try snaking from the rooftop vent (if your snake is long enough) or try to find a cleanout cap you can open and snake downstream from the tub as far as you can.

I've never had much luck snaking through traps. If you can't find a cleanout, you could buy a new toilet wax ring and pull the toilet and snake from there.

Anyhoo, your toilet won't back up until the water level in the tub rises several inches above the floor level. So your problem just isn't bad enough to show up at the toilet... yet. ;)
if water is backing into your tub when the washer empties then the main line is plugged.
I was hoping I wouldn't have to rent a drain auger

But from what you guys are telling me it looks like thats the case. So here's my next question, I don't have any trees or bushes growing in my front yard, so its unlikely there would be tree roots growing in the pipes, but if there was is it easy to discern hitting a root versus hitting a standard clog? And how easy is it really to run one of those draing augers? I have a small house, very simple drain system and I have a cleanout cap on my stack which I can get to from my crawlspace, certainly I can set the auger up and go at it down there, but I don't want to waste money on renting one if its something I can't handle myself
The problem may not be roots, could just be a hairball or a glob of soap residue. If you have a garbage disposer, you may have been collecting a slow buildup that finally reached critical mass. Or one of your kids flushed something. And at the place the kitchen drain combines with the laundry, lint from the washer and grease from the kitchen will form a concrete-like aggregate.

The lint-based concrete is what causes the most headaches for us. Never pour grease down the drain!!

I've never encountered roots, but I'd imagine they would feel "harder" than a standard clog? I'd hold off on the auger until I was sure the snake couldn't get it...
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