Basement plumbing in apartment

Hi all,
I am looking for some advice on how to approach a basement plumbing problem I have. I know absolutely nothing about plumbing. I am just a new renter in a refinished apartment with a basement bathroom. I've haven't had much luck trying to find info specifically regarding my situation. Pardon my lack of knowledge as I try to describe what's happening.

The bathroom: Newly remodeled in a 2FL duplex. The bathroom is about mostly below street level in a brownstone building in a city environment, city sewer lines. The bathroom floor is probably 5 feet below street level. Tub/Shower is about 8" higher. The toilet and tub seem pretty standard, nothing unusual to me, no visible pumps, not low flow.

The problem: I just moved in this week. The first 3-4 days I had no problems. Only thing unusual I noticed was the toilet water in the bowl would go really low but flush ok. No odors from like a lack of water seal that I could tell. Well the last 3 days the toilet won't flush most of the time. A tiny bit of water goes down but it mostly fills to the top of the bowl. Nothing solid was put down the bowl, all liquid. It would usually just drain out after an hour or so, sometimes sooner. But if I flushed again, same problem. Sometimes I would come back and it would flush fine, other times it wouldn't flush. Usually for a long time, not flush one time and not flush next time right after, I mean it will flush fine all morning, but I come back from work that evening and it wont flush (drain) all night. I should be clear, it drains, just very slowly it seems. Like take 30-60 minutes to drain out, I flush it and then same routine.

Last night the toilet was flushing like normal. No solid waste. This morning I wake up and it is totally back up, the toilet is filled with raw sewage about 2" from overflowing (thankfully not overflowing). I opened my shower curtain to horror... raw sewage all in my tub, about 1-2 deep". Oddly enough it didn't smell that much (no idea if that means anything) but it wasn't pretty. My sink was fine and drained fine when I used it only briefly to wash my hands so I'm not sure if it really was blocked up too. I used the kitchen sink upstairs for washing up and brushing teeth and stuff. Nothing unusual in upstairs sink or dishwasher, no blockage or odors.

So I do have a super and called him. He said he has to get the plumber to snake out by the street. I don't know what that means. I assume the sewer line from our building is blocked up? One thing to note is we had a lot of snow and rain last night and still raining now with large puddles all over but no visible overflowing storm drains.

I'm not sure what to make of all this yet. What I do want to know is:

What is the most likely culprit and can you elaborate on what my situation is (typical city street sewage level, etc).
Is this likely to happen again? (I would assume yes unless dramatic measures are taken)
What can be done to prevent this? Pumps? (Saniflow?)

thanks!

First of all, you are a renter and the plumbing is the responsibility of the owner of the property. My best advise, DON'T MESS WITH IT. Definitely do not try chemical drain openers, they are ineffective and cause a hazard for the plumber. It does sound like your main drain is clogged and that requires a professional ti auger or snake from the house to the city main, but even if you owned the property, it's a job for a pro with pro equipment and know how.

If you have raw sewage in your apartment, I think you can get a hotel room and bill the landlord.

hotel

Unless the super okays a hotel room, he might either not get reimbursed, or have to find a different apartment building.

Let us know what happens after the plumber snakes the line out.

Thanks for the replies all.

I was really busy at work this week. The plumber and super went to work at the problem when I was at work. I was told they snaked out the line "in the street" whatever that means. Then the next day... they came in and snaked out my apartment. They also had cleaners come and clean it all out. I still cleaned it again myself afterwards just because... it was pretty gross for someone who isn't used to seeing that (I'm also used to being sterile all day in the operating room lol). It never did overflow the toilet and tub as far as I know thought which is good.

It has been fine so far last night into today. No problems. I used the shower and toilet with no problem. The toilet seems to flush better then ever but my experience is only a week here.

I worry about it happening again. Should a bathroom like this (like 5 feet below ground level) have a pump or something?

Thanks

I own a building that sounds nearly identical. The toilet flushes well with no pump. It's even low flow.
The only problem I did have is wen a previous tenant was flushing plastic tampon applicators. Even though I'm of the male persuasion, I know you're not supposed to flush those! Remember the game "jenga"? Like that inside the toilet's trap!

I can appreciate what should and shouldn't go down the toilet. I've flushed many a condom down the toilet (which I wont do anymore). My girlfriend's flush their stuff down the toilet too. That has to stop. Paper towels, etc. That wasn't the issue with my situation though. I just moved in and never flushed anything down there other then liquid.

The plastic applicator thing is funny. It's funny how people treat a toilet as a garbage disposal. I guess that keeps a lot of you employed though