Alternator question

About a 60 days ago I had a leaking aux fuel pump that was discovered due to starting problems. The fuel pump, associated hoses, and the serpentine belt were replaced (since the belt got wet with diesel).
Now yesterday I had a dead battery and had to push-start to get home. I figured it was a bad battery although it's only a little over a year old. Took it to O'Reilly where I got the battery, they tested and said the battery is good but the voltage regulator is bad. This makes sense because at idle the voltage is 11.5v to 12v instead of the normal 14-15v, and I can charge the battery and everything works until it's soon depleted due to not charging from the alternator.
My question is this: Do you think the two events, leaking aux fuel pump dripping diesel, and later the alternator failing could be related? If diesel on the serpentine belt is a problem, could diesel on the alternator cause it to fail after a couple months? I'm not certain it did get wet, but given the location, it seems very possible.
-Michael

Could be related to the diesel leak. Did you pressure wash the engine bay after the leak? Water could also be the culprit if so.

You need to properly troubleshoot the electric system first.

I had the leaking aux fuel pump handled at the dealership because I was in a hurry. So I'm not sure what they did to clean the engine compartment afterward. 2micron here told me exactly what the problem was a day after I put it in the shop - could have saved $1000 following his advice. Oh well. Just needed a better washer on a connection to the pump, not a whole new pump and fuel lines.

For the alternator I did take it to a local VW specialist (Moberly's) and he did concur that it was the voltage regulator. I picked up a remanufactured Bosch alternator from O'Reilly's since he quoted a remanufacture as well at 3x the cost. He's replacing it now (yep, in a hurry again - really wish I had time to do it myself).