[heatmizr]

Nailed it!
I just did this repair today, thanks to this and several other forums posts. I had the same symptom of fluid leaking between the body and lower trim panels right behind the front passenger wheel.
Getting the inner fender liner out was the worst part.
One thing I didn't see mentioned anywhere - my reservoir tank wouldn't easily pull forward out of the inside of the body. There is a plastic post on the back edge of the reservoir that sits into a metal tab to support and locate it. It is angled slightly down, so if you lift slightly and pull forward it should disengage. Opposite to seat it again when re-installing.

The Front washer pump was leaking right from the body of the pump itself. Grabbed a $20 replacement at Autozone, popped it all back in and so far so good. Beware, there are a few models that supposedly fit, and some are for rear vs front (for a wagon??). Then there is yet another that is for the front headlight washers which is optional as well. No idea why they all need to be different.
My car has neither rear washer or headlight washers. So asked for "front washer pump" and it looked identical to my old one.

The filter screen that the pump intake fits into was totally clean, even on my 2008 328i. Amazing.