Possibly, but if that's what you need to do to survive you will. Finding and maintaining access to (aka defending) a water source is one of the most challenging parts of survival. Primarily because it locks you into a location if you let it and a quality source is a huge draw for populations - obviously.

In scenarios where you're out of municipal water a few days like is happening right now in Houston (Myself and my family have been through Allison, Rita, Ike and now Harvey) then having a water cache for a week is reasonable, though really hard to do, but that's really not what we're talking about.