Heat produced from electrical current (see: Amperature) is what causes tissue damage in organisms. It’s much more effective to use electrical energy create temperatures that are unfavourable than it is zap bacteria.

On another note, the US Army Corp uses electrical current in bodies of water to create invisible barriers for invasive species:

https://www.lrc.usace.army.mil/Missions/Civil-Works-Projects/ANS-Portal/Barrier/