I'm new to this forum and am a homeowner, so sorry if there is a better place I should be posting this. My question is not so much a question but wondering what my issues could be; I am occasionally getting water coming out of the trap where our washer exhaust is. I have a sump pump after the washer and it seems like when the sump pump goes off it pushes water back out of that washer trap (seem my diagram here). I can't say it's always started by the sump pump because I initially suspected it was from too much water consumption in the upper floor.
After further thinking, septic, basement... Hmmm. Unless your septic system is down hill, I am having trouble with the concept that your sump pump is pumping into the same pipe that your washing machine is.
OK... I expect that you have a septic tank. I suspect that you have a pump in a basement pit. The pit accepts the water from the washer, laundry tub, and floor drains, and is pumping that into the septic system.
If you have a toilet or shower, (and probably other cases) that pit should be sealed and vented with a vent pipe. Then the sewer ejector pump inside would pump into the septic tank periodically. Such a system should not be called a sump pump but rather a sewage ejector pump.
It could also be that you have just the washer going into an non-sealed pit with a sump pump at the bottom. Then that is pumping into the septic system. The problem with that is that your floor drains and foundation perimeter drains probably go into that same pit. You are putting a lot of extra water into your septic unless your area is very dry or you are on a hill. Sometimes those systems get retrofit with a manual valve that dumps water outside usually, but to the septic system when doing laundry.
You should probably figure out what you have, although you may decide not to change what works. Do you have a sump pump *and* a sewer ejector pump? That would be the most probable condition to go along with your symptoms
The washer and sump pump are in the basement and the main goes out right after the sump pump. Could it be that my cesspool is full? I had it drained 2-3 years ago but now my boys are older and taking long showers (another issue altogether). Any thoughts/ideas? And the amount of water coming back can vary from a single splash back to a decent sized puddle. Thanks in advance for any help or info.
Anyway, I suggest getting your septic tank pumped again. Ask the worker how long he thinks you should go between pumpings after he has done the pumping. I suggest looking for a local owner-operator for good work and very good suggestions as a bonus. He will probably know what the typical sizes of septic tanks for your kind of house in your neighborhood. He will know how full you were. $200 (make that $300 for the LI cost of living) is still worthwhile for the peace of mind and the education. If you pump it a year too early, that only cost you an extra $100 maybe. If you already needed pumping, that will save you big bucks.
I am not a pro. I do have a septic system and a basement.
Edit:
https://terrylove.com/forums/showthread.php?51597-Unusual-washer-standpipe-pls-help Use of an AAV may not be allowed in your area, but it would definitely be better than what you have.
