You can add 3/4" pipe to extend the auger down as far down as you can lift it back up with a load of dirt until you hit the water table. I'm using it to drill a well for irrigation, water table is about 20' where I live, I dug an 8" hole ten foot down in about an hour and a half and cased it. I'll go the rest of the way with 4" casing to the water table. Works great in my soil which is mostly clay, this would work well for fence posts as well, much easier then post hole diggers.