A borehole starts before the rig arrives
The important questions are site suitability, permissions, likely yield, drilling access, power for pumping, storage, treatment and long-term testing.
What to ask suppliers
Ask what survey or geological information is used, what is included in the quote, how yield is tested, what water testing is required and who maintains the pump and treatment system.
Caution
Borehole water can involve legal, environmental and drinking-water responsibilities. Treat this as a planning checklist, not permission or safety advice.