Well that explains it.

"The drinking water for Washington, D.C., and surrounding areas tested positive for six pharmaceuticals." From CNN.com found on March 10, 2008.

Hmmm, let me see:
Valium--see no evil, feel no evil
THC--they didn't inhale!
Prozac--for the rose colored glasses
Oxycontin--they don't feel your pain
Ritalin--too late, they never did pay attention in school
Viagra--enough said

For the real story, go to the link.
The sad thing is that doctors were always told to flush expired sample medications down the toilet. Only recently did I learn that pharmaceuticals are supposed to be otherwise disposed of. The question is where? In the trash that the homeless regularly dig through in my neighborhood? One article suggests that you mix the used medications in with something unsavory like used kitty litter. What an awesome idea. Quick, let's mix up a batch right now! Even the rats won't eat that!
Of course it isn't medication samples that are the main source of the problem. It is the other stuff we flush. All the medications we take and then excrete unmetabolized. Who woulda thunk it? I always assumed that sewage treatment took care of it. Turns out if our livers don't break it down, our sewage plants may not either. Water filters like Brita aren't effective either.
Of course there is no reason to panic. The amounts are minute and we have no evidence they are harming us. But still room for thought. Oh, and bottled water may not be any better. Besides think of all the plastic waste the bottles generate and all the trucks, boats, trains and planes moving all that tap water across our planet to give us the placebo effect that it is better liquid than what one can get for free at home.

Speaking of THC, I'll close here with a final quote from that bard and social historian of the sixties (and he sure did inhale) Tom Lehrer.

"Lots of things there that you can drink,
But stay away from the kitchen sink.
The breakfast garbage that you throw in to the Bay,
They drink at lunch in San Jose."

If you haven't already seen it, watch Lehrer sing it on You Tube. It will brighten your day.