We live not far from a river. When the river gets high, our water table goes up and we get water into the sump.
We added on and included a full size basement in the new part, about 20 years ago. The old part of the house still has the duck under everything type of basement under it.
About 15 years ago we went through a 500 year flood for the river. The river stayed in its banks, but the water table went way up. The old basement experienced just a little water coming out cracks in the floor. Running right over and down the floor drain.
The new basement, which is about three feet lower was a mess. Our pump did not quit, but it could not keep up. At the river crest we has five pumps in the sump well and the top one quit cycling off and on. We did not have a lot of water in the basement area, but there were times we did not catch it in time to add another pump. We really sort of rethought how to fix it for the future.
Fix it may not be the right word, but rather deal with it better. We now have two permanent pumps in the pit. Both plumbed separately and both wire on separate circuits.
We took about four feet of the drywall out at that time. Cut the insulation off. We then added the Styrofoam type board. We have an 18 inch plain cedar board for the base. The foam board we cut so we could just get it out of the stud cavity, with the base pulled.
Numbered every cavity and piece of foam board. If it happens again, we can just lay it out to dry and clean if we have to and install it back where it goes.
We have never seen water coming in through the walls. It is always been through floor cracks. Of coarse by that time the pumps are running very regular in the pit.
I have the two pumps in the pit, one just a little higher than the other. I also have two identical pumps, all plumbed and ready to install. I have some heavy duty rubber couplers, that make it a job that take just a few minutes. I also have two new identical pumps in the box sitting on the shelf.
I actually ran some pex to install a water powered back up pump. All in all, I decided to more than they could pump, it would be a waste. I just put a faucet on the pex. I can just open it and fill the pit on a monthly basis to make sure everything works.
We have had a few 100 years floods since we have done this, and it seems to have worked. We also have the water alarms too.
I would say about the only thing left that we have talked about is a whole second pit in the opposite side of the basement. If we do that I would have the same pump set ups I have in the first one.
Of coarse if power goes out we may be in trouble. I do have a generator and have it sort of ready to run if needed. We have also talked about a whole house generator that would kick on with an outage. What we have now only works if some one is here to do it. No automation at all.