From the World of Reality, Civil Engineering, treating wastewater CAN BE, and in some instances IS, done to make it cleaner than the quality of local groundwater that is withdrawn for drinking water treatment purposes. The process of Advanced Wastewater Treatment (AWT) has existed for decades, is resoundingly EPA approved, and in some locals, AWT discharge is of significantly higher quality than groundwater.
The answer to the question is "NO!" The General Public is averse to allowing AWT discharge water to become the input process water for potable water treatment. The stigma of drinking treated wastewater is too strong to overcome in the General Public's mind.
Food for Thought (and that phrase in this discussion is probably "fingernails across a chalkboard" for some), through wide-area discharge and groundwater RECHARGE, the Earth and its bacteria are the constant proving grounds that human wastewater of EVERY persuasion, even untreated sewage, is transformed into process water for drinking water purposes AFTER a period of latency in the soil and migration from the area of discharge to the "Ocean of Groundwater" from which potable water for treatment is withdrawn. Think on that a little bit...
There are "10-State Standards" adopted by U.S. Municipalities for construction of On-site Potable Water Wells and Wastewater Treatment Facilities (drinking water wells and septic tanks and drain fields) stipulating minimum distances between such improvements, as well as surface water bodies, to preclude short circuiting of the Earth's natural cleaning processes. You do want clean drinking water and you don't want sewage discharge going directly into the well head or where you and the kids swim.
The water is never going to get cleaner until you get the cows out of it upstream.
