Anyone know plumbing?

[GoldenRivet]

Just had a new experience in my rent house, and plumber is on his way tomorrow morning. but...

The 8 yr old was taking a bath, and laundry was going.

keep in mind there was no drainage from the bath at this point.

im sitting here on the computer and i hear bubbling, i go and look and the toilet in both bathrooms is bubbling in the bowl.

kid gets out of the bath and drains the tub.

now both toilets are really bubbling like a couple of percolators, she went in her room and a few moments later the bubbling slowed and seemed to stop

I noticed a wet spot in the carpet outside the bathroom and upon entering the bathroom i noticed about 2-3 mm of water spread through the whole bathroom. WTF? kid takes a messy ass bath!

as im toweling it up, i realize its coming from under the wall, and water is coming in about as fast as i can get it cleaned and i also take notice that there is still about 3 inches of water in the tub that is not draining down the open drain.

I yank the return air vent cover outside of the bathroom off and look in under the heater and from the slab drain for the AC unit water is bubbling out. It was warm water... it was tub water coming out of the slab drain!

My assumption is at this point that the drains are not venting and the water has no place to go except backwards.

the tub slowly drained down to empty, and the bit of a backup subsided, the water is cleaned up, but not sure really why that happened other than poor ventilation of the plumbing system.

My guess is that the plumber will show up and snake the drain vents and everything will be running smoothly again.

thoughts