ding idng ding ding ding big blue 77 got the answer right as well as BC.
your main sewer line from the side of your house to the city's line is clogged.
but BC cracked me up, if you are having problems with your main sewer line you need to get a Roto-Rooter. ANd clean out your main line. if you have never used one, pay someone to do it, I have had clients break their arms trying to do it themselves. A rental can be about 45-75bucks, most people charge you 75-100. I charge 60 for old customers, 75 for new ones.
sorry to say that you cracked me up BC, but that's a pump you're talking about, it works by compression, and it can be bad on an old house since it can actually loosen up the old plumbing and cause a drain leakage, especially if you use it on the bathroom in the basement you will have water shooting from your tubs sinks and comodes on the first floor. and besides, there SHOULD BE a One Way Valve that allows water to flow one way only, so backflow will be stopped. It needs to be installed if the toilet in the basement is lower than the sewer line's level. You see, if your toilet is lower than the lever of the sewerline, you will have that water drained to a trap, then have that wasted pumped out and up a line to the main sewer line. if that valve isn't installed sewage can go through and probably ruin the pump and make a mess. But if it's level with the sewer line, then oh boy you have a deep one.
Take it from me guys, I'm a master plumber and a master electrician. Been doing this stuff for a long time now.
I suggest that you get a roto-rooter and get your line cleaned out. And if you get someone to do it, and they come with a water hose with a dart tip (it's used to unclog with a jet stream) or a push tape, send them back to mama. An electric Roto-Rooter works best beacause it will tear up all the roots that it may have clogging the line up as well as other materials such as paper towels, facial cloths, and even Kotex/Maxi Pads. Yes, I have found those as well, so ladies, please don't fush those down the comode, especially tampons since they can clog up the main line. Unless ofcoarse you want to pay a plumber to clean out your sewer line.
so there you have it Maface, your main sewer line is clogged fromt he side of your house to the city's limit. and if you don't have a clean out on from the City, call them up and they will be forced to put one at no charge, remember it's in their property only though. a clean out in your property is your responsibility.
Rememer you got a Master Plumber and Electrician in the house