Blocked or dirty pipes. id call a plummer ASAP.:)
You have a minor clog downstream in the drain.
Check for the drain hose or pipe in your unit so that it is not clogged. Through the ac process water is collected and thus needs to come out. If the drain is clogged water will be trapped and the blower will pick it up and send it through the vents.
The drain is getting plugged and the toilet is lower than the washing machine drain so it is easier for the water to come up in the toilet than to go straight out the drain. Put some drain cleaner down the drain where the washing machine drains and that may solve the problem.
BAD venting causing negative pressure / back siphoning
You can completely drain just do not leave empty for very many days or it may float like a boat.If you have a dew drain water will continue to come back into the pool from the main drain if the water table is high enough.
when your engine is hot it causes the water to boil and the water and the anti freeze will come out of the overflow pipe.
The drain from the washer to the main line is getting plugged and the floor drain is easier. Drain cleaner in the floor drain should take care of it.
There is usually a drain plug on the bottom, release this and the water will come out.
A drain basin is an area of land where rain water and melting snow come together to drain into larger bodies of water such as rivers, lakes, reservoirs and eventually the ocean.
You have a blown head gasket.
The main drain is plugged. Not completely, but enough that it is easier for the upstairs water to come out in the shower and floor drain instead of going out the drain.
What causes the shoreline to change well that's and easy question you might not see it and but when at night the waves come through and back so from the ocean the more water that comes from there the bigger the wave the bigger the shroreline
Most likely it is caused by an air leak somewhere in the system allowing the filter to drain back to the pool through the suction lines. You will probably see DE in the pump pot as well.