Washer water overflows basement drain

Hi there...I have always had a problem with the washer water overwhelming the floor drain in my basement. It seems that the water drains too quickly for the drain size? I just had a new septic system installed because my drain field failed so I know that it is not a septic issue. All other water fixtures in the house do not cause the drain to back up. I had the line snaked prior to septic installation however by the time they got the septic installed I most likely had a little backup into the line outside. It never made it to the house.

The house was built in 1964. When the drain overflows, there is some black "stuff" that come up. It is very fine and has a smell to it. I don't know if it some sort of "oil" from the pipe. The main pipe from my upstairs to my downstairs is black so maybe that gives you some idea of what type of pipe was installed.

Any suggestions other than restricting the water flow from the washer tub down the drain?

Thank you.

What diameter is the drain pipe? Current code wants a 2" line. The black stuff could be crud on the pipe walls and a good snaking may resolve that.

The drain itself might be 2 inches but I think it then goes to some sort of a p-trap and I don't know if that is smaller or not. Everything is under concrete. I virtually have to plug the sink drain almost closed to really restrict the water in order for it not to come back up. It does not come back with the dishwasher which goes down the same pipe. However, the pipe from the dishwasher is smaller and then goes to the larger pipe so the flow I guess is restricted by the smaller pipe.

If the washing machine did not cause these symptoms before, the problem is most likely a partial blockage in the line. The line can be snaked out or it can be jetted, but it needs to be cleared for it's entire length.

If there is still an issue after doing that, it may be best to run a camera down the line to look for a more extensive problem.

This has been an ongoing issue for years. I did have it snaked about 2 months ago but then did not use the washer because the septic needed to be replaced and we had to conserve water. Is the P-trap 2 inches in diameter? Just wondering if we can even get a camera down there. The main drain cover would have to be jack-hammered to get it out I think. I personally hate my old house!

Are you sure that the basement floor drain even hooks to the septic? In old houses is was somewhat common for greywater and floor drains to drain to a drywell.

Floor drains come in all different sizes, and the trap should be the same diameter as the pipe. Most of them have a cleanout port which bypasses the trap for snaking.

Old houses are great, but they can be more challenging to deal with.

The house is so old I didn't even know where the septic was until I had to have it replaced. What the heck is a drywell? I did have the drain camera done but from that large black pipe leading from the upstairs and out to the septic tank. When we turned on the water for the washer tub, when the camera was in there, we just saw drips but at that time it was clogged to the point that nothing could be put down there, even the smallest bit of water. The plumber assumed they met up. The snaking was done on a different day than the camera and the drain appeared to be draining nicely. However, since the septic was out we did not use that drain at all. No dishwasher, no sink, and no washing machine for 2 months.

Floor Drain Might Not Connect

First, a "drywell" is simply a bunch of gravel. Many times floordrains simply connect to a small pit of gravel underneath the concrete slab. They are not intended for washer drains, but maybe condensation from an Air Conditioner or the over temp/pressure valve on a hot water heater.

That said, if a plumber snaked your floor drain he should have noticed quite quickly if it was a drywell.

If actually connected to your house drains, it sure sounds like the floor drain is clogged.