I live in the Michigan basin. The lower peninsula was scooped out by the glaciers, and bedrock in the center is down 16000ft. Sand and gravel were left behind.
The bedrock here is shake, but down about 500 ft. My town has wells that are about 110 ft deep. The water has a seasonal TDS in the 640-700 range. The minerals are from the pulverized limestone, dolomite, iron bearing rocks, and so on. The town removes the iron, noting else.
I brew with RO water.