your drain has a restriction in line and needs to be snaked
Improper venting.
It might be plumbed wrong -- or either your sewer is stoping up --
Sounds like the washing machine discharge is fitted to the main drain in the wrong place and it's discharge is filling your toilet. It's possible there may be something of a blockage just after the toilet, causing a backup. I would try to snake the the pipe from toilet out. You may even have to remove the toilet from the floor and do it there if there is no access underneath (like a basement or a crawlspace). I have snaked main drains from the toilets many times, and it's a pain having to re-re the toilet, but often it's the only way.
Either dried out P-trap or possibly no p-trap or break in drain line after p-trap
There are multiple reasons why your washing machine might not drain. The drain line could be clogged with debris or even clothing, the pump pulley could be frozen, or the pipe that the washer drains into could be clogged.
When the washing machine drains, it can cause the toilet to overflow because both appliances may share the same drain line. If the drain line becomes clogged or blocked, the water from the washing machine can back up into the toilet, leading to an overflow.
Partial blockage. Snake the drain.
what would be needed to drain a washing machine up from a basement? We have power and water, as the water heater is in the basement, but the drains are about five feet up.
Because the washing machine drains down the same main drain and it's suction as it goes by is trying to suck the water out of the under sink U trap.
Improper venting.
If you have septic and leachfield either your septic tank is full or you have a plugged pipe or leach field. Call ana septic company or excavator. If you have public sewer call municipality. Only other quess would be if washing machine goes into a drywell which is not draining.
You can drain it directly into a drain pipe. Just make sure the the top of the drain pipe is even with the top of the washing machine. If not, the water from the washing machine will drain all of the time. There is no valve in the machine to stop the water from draining. The washing machine drains using a pump motor.
It might be plumbed wrong -- or either your sewer is stoping up --
make sure your drain hose is not covering the whole circumference of your drain pipe or you wont get good ventalation. Option 2 vent pipe in wall could be slightly plugged.
The washing machine works by filling with water and rotating. The operator has to put in soap, bleach and softener. The washer agitates, then spins, then fills with water, then rinses by agitating, then drains again by spinning.
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.
Yes you could, but it's usually not allowed by plumbing codes. Another point: Sometimes in Britain the outlet from a washing machine is joined to the under sink waste. I lived in a house with this arrangement once, and every time the washing machine was on you got bad smells from the drains, so I wouldn't recommend it.