Jeremy,
From your last post, it sounds like your "problem" that you are referring to, is a low water level in your house batteries only. If so, you can not blame that or the alternator failure, on a bad cell in one of your cranking batteries.
The water level in your house batteries should be checked every month because some batteries need to be refilled that often. If you are finding your house batteries "very low" on water you are not checking them often enough.
Gerald