I drain as much water out of my unit after every outing.
I know there is still some water in the FW tank even when drained as well as in the lines, this water gets hot and sits, it does not take long for the water to go stale.
As posted above a little bad water goes a long way...
Drain your system as well as you can, add some fresh water and run thru the lines then do it all over again.
2016 F350 6.7L LB CC Reese 28K 2014 Chaparral Lite 266sab
"Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety." 2014 19 days camping 2015 17 days camping201620 days camping