Help Me Devise a System to Keep Basement Dry

Hi – just bought our brownstone in BedStuy and refinished by basement as part play space. Over the last year I’ve owned the place, there has been no water in the basement, but I understand I have to accept this eventuality, so trying at least to have a mitigation system.

I currently have a pump in the basement that pumps the basement sink into the sewer main. There is a pit in the ground that holds the pump, which is all located at the front of the house where there is a slop sink. The pit/pump has a check valve on it, but the sewer main does not.

I’d like to devise a system where I prevent any backup from the street from coming in (i.e., add a check valve to the main) and then more manually eject the roof rainwater that can’t get out past the check valve from my floor pit by pumping out the hatch. Basically, if I’m going to take on water, I’d prefer it to be from my roof than the city’s sewer system, and would rather have it collect in the floor pit rather than backup out of my toilets and drains potentially on higher floors.

Thoughts?

Separate, but relatedly, I had RR come to view the sewer line (almost $1K?!) and they quoted me $6,500 (after “discounts”) to have the sewer line descaled. That seemed outrageous (and we’re waiting anyway, as it was in good enough condition), but would like this done if I can get done for a few thousand. $6+K to run an auger seems bananas.

Thx!