Create a SuperFlat world.
Go to a village or two (usually found in every city at least once).
Look around farms (e.g. wheat or carrot) for a water flow that has spawned incorrectly outside of the bounds of the water that is in the regular place.
I find this issue in both local SSP and in SMP on servers I create.
Duplicate of MC-11280, please use the search function to see if your bug has already been submitted. Currently over 55% of tickets are being closed as duplicate.