Do you drain your down spouts at least 10' away from the house? Also have to pack dirt clay so any run off goes away from the foundation all around the property. The house by me in the low lands all were built with french drains and sump pumps due to the low water table. New construction is on slabs and they finish the attics with bonus rooms to get that extra space.
Where the red dots are, are where my down spouts are. Problem is I don't have 10 feet of clearance around the house so I try to extend them as far as I can. when we redid the yard last year I regraded the back to slop slightly away from the house.
The problem was mostly crappy/no gutters around the house, but that's all fixed and it seems to be flowing well. The problem this time was a leaky outdoor valve that was 3 feet from this window, water would saturate in the ground and bubble up from underneath, filling the window well.
Before we moved in there was no gutter here so this window has flooded multiple time before and after we got the house. I know because I found mold and had to tare the wall down this weekend along with installing a glass block window....