One of the commode, which is almost never used, fills up with water by itself (no flushing). Worst is when it starts overflowing and there is water almost everywhwere. A plumber once came and ran the snake and said it is clear now. However, it just happened again (no one has used the commode since the plumber came last time). Any suggestitons.

I posted this question in other question by mistake earlier.

This is a really odd problem. If I understand this right, it's overflowing over the top of the bowl? Or is it the bottom of the toilet?

Is the water clear?

More importantly, does the water move with the wind?

Usually toilets empty. Filling is a lot harder.

Now I do initially suspect a vent issue although a clog or other improperly laid out plumbing can also be the problem.

For starters, turn off the water at the bottom of the toilet and check for the problem in however long it usually takes and also check the tank water level before you turn it off and if the problem happens.

Snaking the vent and doing a video of the pipe are possible ways to find out the problem.

Where is this located in comparison to the other bathroom? What KISS said above is true, but...

If this toilet is in a location below the other bathroom, (like in a basement) there may be another problem.

Answer the above questions. If this is a basement toilet then you have a blockage down stream from it that must be snaked. Good luck, Tom

Its only 1 floor house. This commode is next to the washer dryer.

It happened again today and it seems to be linked with the washer. Today, the water that came out appeared like washer (soapy) water. So, basically my washer is not draining properly. It comes out from the commode. It is overflowing from top of the seat .

So, snake the washer drain and you'll probably find a lot of lint.

Now wasn't that easy.

As I stated in a earlier post, "you have a blockage down stream from the toilet that must be snaked."
You can snake from one of two places.
1) You can pull the toilet and snake from there **OR**
2) you can snake from the washer roof vent.
If you snake from the roof put out enough snake to reach the base and 20 feet more. Good luck, tom