Which would be a better water source?

Question

There are two sites, One has sandstone and shallow soil cover with moderate slope. The other is granite with little soil cover with a steep slope. This is for a town of 8,000 people.

Answer 1

shallow soil cover with moderate slope. It just seems better.

Answer 2

I'm thinking that the sandstone and soil with the moderate slope would have better filtration properties opposed to the steep sloped granite.

The granite site might serve better as a reservoir than a source.

Answer 3

Neither has much soil cover to protect the aquifer from surface contamination. Sandstone would hold more water per unit volume unless the granite were highly fragmented. Delivery to the plant thru the aquifer would be faster through the granite. A lot depends on the rate of recharge of the aquifers. Hire a hydrologist and take his advice.