As of last week I suddenly started experiencing sporadic overflowing out of the drain pipe the washer hose discharges into. I thought initially it must be some kind of clog in the system. The drain for the washer is a 2" pipe, which enlarges to a 3" pipe after the P-Trap in the wall junction, which is approximatly 3-4 feet below where the drain hose fits into the wall. I've already fully checked out the washer... it's not that, the washer and hose are working fine.

What's odd about this is it only happens sporadically. I have a septic leach field on a private sewer system, so I made sure I wasn't having issues with my lift station or septic tank was full, those both seem fine. When the washer is discharging, or water somewhere else in the house is turned on, I can pull the cap off the main clean out, outside, and see the water rushing by so I'm hesitant to think there is something in my main sewer pipe.

I have a crawl space and there are three clean outs on the 3" pipe that the washer drain enlarges to, one at the first 90, one at the second 90 and one at the 45 right before it enters the main pipe. The rest of the house plumbing enters this 3 inch pipe at one point or another and we've looked in all these clean outs to no avail. Nothing seems to be blocking them, and they are all draining fine. I've taken a snake and ran it down all of them as far as I can (approx 50 feet) and haven't "found" anything. I've put draino down every opening I can find.

Since it happens sporadically I thought maybe then it was a venting issue, so I went on the roof (I have two vents) and put a fish tape down both of them & a flashlight. Nada. I'm out of ideas. Everything worked fine up until last week. No other fixures (Ie. Shower, toilets, sink) in the house are acting weird or backing up. I was able to do 6 loads of laundry in between the initial issue and it worked fine, then on the 7th load... water everywhere.

If it's going to do it, it does it right away, (within 30 seconds of the discharge starting) and if I hit the water stop button on the washer to stop the discharging the water goes back down the pipe right away. So it's not that it isn't draining at all, it's like there's too much water for it to handle, but it picks and chooses when that is. The main sewer line is a six inch pipe which should be fine plus we've never had issues before.

I've spoken with a plumber and he's just as puzzled as I am? Could there be just a partial blockage somewhere? Or does this sound more like a venting issue? Maybe something crawled/feel down there and I just can't quite see it? It's the sporadic issue that has me so puzzled.

I'm not an idiot, but I'm also not Mrs. Plumber, I'm open to ANY suggestions... the waiting list for a plumber up here (I live in Alaska) is awhile and I'd like to do anything I can to be proactive.

Thanks,
Angie

Do you mean that you did 7 loads of laundry back to back or that its been 6 loads and several days since you had the problem?

I ran through six loads back to back, one right after another.

I would say that you have a partial blockage in th sewer line very close to the washer, possible in the washer stand pipe trap. Possibly a lint build up in trap. Snake the washer stand pipe. You should be able to get a small hand snake through the trap. You could seal the connection between the washer hose and the stand pipe with something like duct. The force of the water under pressure may clear any blockage. However, if washer starts going out of balance remove tape.

That's a good idea, I hadn't thought of that. I tried suction with my shop vac that will suck your arm off if you're not careful but I think it loses a lot of use once you get a ways into the pipe.

I'll try that. Thanks!

If you are on a septic tank 6 loads back to back is way more than your tank was designed to handle. I'd recommend that you not do more than 2 loades per day. Try that before you try plumbing repair. How to Care for Your Septic Tank and Septic System (http://homebuying.about.com/cs/septicsystems/a/septic_care.htm)

Well I had Mr. Rooter come over and of course the first load we ran through was fine. Then the second load backed up right away, they said from the sound of the water flow it sounded like a definite vent issue. When they went on the roof they couldn't see anything in the vent so they power augered it and found a bees nest had closed off most of the pipe. Obviously that would be a problem.
It's not the water load to the leach field, it happens right away if it's going to do it, like it either vents or it doesn't. After they got the bees nest out we ran two loads of wash through, and it worked fine, then this morning it backed up again. Now we're thinking maybe it was a venting issue that turned into a blockage issue, maybe the cone part of the nest has gotten lodged somewhere in the system?

Oh I should also add they augered the line between the top of the drain down through the PTrap and there wasn't anything there.

Either you misunderstood what they did or they are way off. They should use a sewer rodder down the vent all the way to the basement or lowest floor and then 20' more. This rodding will not reach or touch the trap. They may in fact moved your clog from the vent into your drain line, I'd call them back asap. It is not uncommon for them to get a call back.