When it rains it pours ? well, okay when it steams it pour-overs.
I posted a while back about if large boilers risked stale water and if double boilers in particular are likely to have stale water in the brew boiler.
Source: http://www.toastedfoot.com/2011/07/whats-in-your-humidor-paul-maldonado-of-maldonado-dynasty-cigars/
Source: http://www.hawaii-aloha.com/blog/2011/12/27/hawaii-christmas-with-a-touch-of-spanish-flair/
Source: http://www.toastedfoot.com/2011/10/cigar-press-release-new-from-la-gloria-cubana/