Does the infiltration-percolation processes filter water that reach the ground reservoirs to an acceptable standard or is there any need for further treatments.
It depends on the type and quality of the Vadose zone through which water is infiltrating and accumulating in aquifer. If the Vadose zone consists of properly graded material water quality in aquifer generally would be of good and may not require treatment. However, if aquifer consists of carbonate rock/ material it may require treatment, even if it is recharged through good quality Vadose zone. Best wishes.