Some of the approaches sound very sensible, such as regulating groups of contaminants instead of doing them one by one. One important factor that was left out of the discussion at this point: dual systems.
Why treat all that water up to drinking water standards, when most of it is not consumed? With a separate piping system reserved for highly treated water for drinking and cooking, lot’s of money can be saved on treatment. Dual systems can be cost-effective especially in new areas, when all the infrastructure goes in at once. And, while we are in the process of replacing a lot of old infrastructure, we should think about dual systems there, as well.
Keep in mind also that water quality deteriorates significantly after it leaves a water plant, as it travels through the distribution system. Dual systems, with a dedicated piping network that can help prevent this deterioration, merit EPA focus for this reason, as well.