Sour can mean different things to different people. Best case scenario is it fades over the couple of weeks. Worst case is it gets worse over time and would indicate some kind of infection. Either way, I always topped off with just filtered tap watet, no boiling.
Sent from my ADR6300 using Home Brew Talk
Draft 1: Lightly smoked Weizen
Draft 2: Belgian Wit
Draft 3: Rauchbier
Primary 1: German Scwarzbier
On Deck: Belgian Brown Ale, Pale Ale, Stout