I think that in general, the problem with water barriers is that they work well on humans, who need to breathe. But, depending upon the type of zombie universe in question, zombies may not. They may be able to just walk along the bottom.
EDIT: And one other complication for the zombie apocalypse survivor who wants to set up near large, accessible sources of freshwater:
b. (U) Operational COG #2: Potable water sources (PWS)
i. (U) Zombies do not drink water, but humans do. Humans typically cannot survive longer than 10 days without fresh water. Zombies will likely be drawn to potable water sources by the presence of human food sources that zombies prey on.
I think that in general, the problem with water barriers is that they work well on humans, who need to breathe. But, depending upon the type of zombie universe in question, zombies may not. They may be able to just walk along the bottom.
EDIT: And one other complication for the zombie apocalypse survivor who wants to set up near large, accessible sources of freshwater:
https://www.stratcom.mil/Portals/8/Documents/FOIA/CONPLAN_8888-11.pdf