When drilling a well make sure that your 50ft or more from septic systems or any other source that would taint you water.
How deep do you drill?
You only drill until you hit good water. A deep hole does not make water,only water bearing formations do. If the water bearing sand is at 100ft and you drill 150ft you still have to set well screen at the 100ft water sand level. The rest of the drilled hole is just a waste of well casing. People are odd, what i mean is one neighbor on one side has a 200ft well, the other neighbor on the other side has 250ft well so the neighbor in the middle wants a 300ft well to show everyone else up. Also water is one of the greatest solvents in the world. Every layer of limestone,iron ore or one of many thousands of other minerals water goes through it desolves.Thats why the deeper you go the greater the chance for hard water.
One more deep drilling tip, drillers charge by the foot.If he hits good water at 50ft he's going to keep going and hit deeper water tables below. Remember shallow wells do not pay motor home payments - deep wells do.
Drilling rig plans book .
This book covers step by step how to build one of the best portable drilling rigs around.You will need basic welding skills and a chop saw would help.