Hi :-) I purchase a townhome approximately a year ago. It is 3 levels with the bottom level being a walk out basement (underground in front) walk out in the back.
We had a small earthquake in the area last summer and after that, I noticed during BAD rain storms, the basement would leak. It took me 6 months to finally pin point the location of the leak. My neighbors townhome sits about 1-2 feet further forward than mine. So the back of my house juts out about 1-2 feet further out. The water seems to be coming in where her house meets mine, about 1-2 feet from the back of my house on the wall I share with her. The majority of the water seems to start (come from) the corner that forms where the land is graded TOWARD the house and there appear to be small cracks in my cinder blocks and mortar. ADDITIONALLY, her house (basement) is about 1 foot higher than mine (maybe like 8-10 inches) due to the slope of the hill our houses are on. Therefore, the water sits in the corner slightly higher than my basement. The area by my sliding back door rarely ever gets water... just that section of the wall. If it is ENOUGH rain (like the monsoon the DC area got last fall) then a decent amount of water will come in and create some "streams" and puddles but not a consistent amt and it dries quickly!
I had a basement waterproofing company come out and try to charge me $4K for a sump pump. NONE of the houses in my neighborhood have one (although he tried to tell me my neighbor does, which she confirmed she does NOT).
Do I really need a sump pump? Or is there an easier fix? I already plan to paint my cinder blocks with waterproofing sealant once all work is complete before I close the drywall back up.