Home Improvement

If it comes up the basement drain, then the obstruction is further down, and so you can't really flush it from the drain and out. You need to find the sewer service well further out and flush it from there and in.

It's likely a broken pipe taking in sand or branches, so flushing it won't be a permanent fix. A plumber can probably fix it from outside too, so it doesn't have to be very expensive.

You don't need to waste your money on snakes and that kind of stuff. If a regular hose on full blast can't loosen the obstruction from outside, then you need a plumber anyway.

You need your drain line scoped for obstructions. You could possibly diy it to a certain length but it may not be enough.

You have my sympathy on the basement flooding issues. Been there. Thankfully not sewage backup in my case.

it's definitely not an issue you want to let go for long. If there's an obstruction, it will get worse quickly as more solids go down the drain. Easiest way is to just hire a plumber. Complexity and cost are going to depend heavily on the cause and location of the obstruction.

If you want to try to DIY it, you could try to snake the drain but on a 3 or 4" line you'd need a good sized power auger to make any serious headway.

If it were me, I would get a sewer inspection camera. Low end ones start at less than $150. This is really the only way you're going to find out what the root issue (no pun intended) is outside of paying a plumber to come do the same thing. A large wet dry vac also comes in really handy in these situations.

How old is your home and what's the sewer line made of?

I'd at least get a plumber to check it out. You could snake it yourself probably but you could also make it worse. If the pipe's broken, you might as well just get more debris falling into it and clogging it further.

A regular plumber visit/check usually isn't that expensive. Not cheap but far from 20k expensive.

It could also be connected to your flooding too, so you probably actually want to at least evaluate the damage ASAP. If the pipe's broken, you just have a convenient pipe to drain all the rain water straight to your basement.

So this is likely one of two things: a clog in the line or the sewer line between your house and the service is broken. You didn’t say how old the house was, but the older it is, the higher the chance the line is actually broken (especially if you have any drainage issues near the foundation or foundation settling issues). No matter what you’ll likely need to figure out what the issue is first by having it scoped and then figure out your next steps. Hopefully it’s just a clog!

Source: had a broken line in a fifty year old house. It was awful and definitely not cheap.

It might be a few hundred to scope the main sewer line but you could probably find promos to lower the cost. There's a "one stop shop" in my area that's advertising scopes for $30, but they do plumbing, electrical, and HVAC and I haven't heard of them doing any of those particularly well. If you find a company like that just be ready to put up with their sales pitch and then keep the video to run it by a different plumber for a dimebag or a case of beer or maybe even some real money.

Do you have many big trees on the property? That's usually the biggest cause for backups like what you're describing: roots sneak into the sewer line, then keep growing/expanding and catching all the toilet paper flowing by and then just turns into this big dumb obstruction that constipates the whole line

Might be worth a look yourself:

Anykit USB Endoscope Camera with 8 Adjustable LED Lights, Borescope with Semi-Rigid Snake Camera, IP67 Waterproof USB Inspection Camera for Phone & Tablet (33ft) https://a.co/d/aiNASM6

DIY what, exactly?

Can you put a sump pump in?