I don't know what you mean by 2/3 sharing. But, a lot depends on the type of house, insulation, age of home, type of appliances, size of home, weather in your area, etc.... BUT, with that said, on average I would think a gas/electric bill is about $150 per month (averaging all months, some less, some more) and an average water bill is around $45 per month. So you'd be looking at around $200 per month for all 3. But again, if you keep your home very warm in winter and very well-air-conditioned in summer, your bills coudl be double that.. If you have bad insulation in an old home, it could be triple that. If you are looking at homes to buy, ask to see copies of the current owner's utility bills. That will give you a better idea than any help I can offer you.