With sources of freshwater all over the world now showing at least trace signs of pharmaceutical pollution, is some kind of global superbug brewing?

I'm also fascinated by these drugs' effect on the landscape; in other words, millions of pounds' worth of loose pharmaceuticals will surely form a detectable layer in the soil given time.

Thousands of years pass; then millions. The rocks you're looking at in the wall of that canyon are made of lithified Prozac. Tylenol Gorge State Park.
A deltaic geography of sedimentary Tamiflu is eventually mined as a building material; temples of this unusually smooth rock are built; visits to them are believed to help prevent infection.
And how will this affect plants? If river grasses and trees begin to accumulate this novel class of mineral, taking pharmaceutical-rich waters up into their roots, will it change the way they grow?