Yes, trace quantities (ppm) that are not metabolized by the person taking the medication (birth control pill, etc.) do, indeed, find their way into the sewage system, where they are diluted by "regular" sewage, flushed water, etc.. The concentration of the active agents in these medications are then further reduced during their passage through the biosphere. Eventually, they can wind up in our groundwater, but by then, the concentrations are in the parts per billion.
So: Your point?
Regards,
My point was my last sentence.