I think this is a slip-up, but could be wrong.

When Katherine is awoken from a horrible nightmare

by Ben, she goes downstairs and pours her self a

glass of tap WATER. Earlier at the livestock farm,

she mentioned that all the water in the town was

contaminated, or otherwise blood, unless u had

well water. The livestock farm were the ones with

the well water, not Doug's house.

And even if so, in The Bible, wasn't the first plague that ALL water turned to blood? So shouldn't the well water have turned to blood as well?

The slip-up was that the tap water was WATER.