First time post, so go easy on me.
Waste water backs up into our kitchen sink (a couple inches) during washing machine drain cycle, but quickly recedes once the drain cycle ends. Had plumber snake the line twice (once down the standpipe and once from the city cleanout in yard) but the problem persists, so I don't think there is a blockage. I assume it's just too much water, too fast, for this 40 yr old slab house; or the standpipe isn't vented properly...
But here's the mystery: When this situation happens after heavy rains, water also comes up from two mystery pipes. One is located in our broom closet by the laundry room, the other is located in the wall behind our guest vanity on the other end of the house. (See photos)
I jammed some plumbers putty into one of the pipes to cap it off after this happened the first time, to see what would happen. That's when I discovered the 2nd pipe behind the guest vanity (because the water had seeped under the wall and into the bedroom)
So, what are these pipes? Where do they come from and where do they go? and why does water come up from them and flood my broom closet and bedroom!?!
The mystery continues...