Electricity cost on a 4" well

[Jim S.]

I just closed on a duplex with separate meters, the 4" well is wired to the one tenant. The house has 6 adults and one 2 year old. Each unit has a dishwasher and washer/dryer. I reduced his monthly rent by $10 to compensate for the electricity he pays for the well. Is this even close? Under these circumstances would you expect the electricity usage for the well to be around $10 or $100. I know it's hard to say for sure but just trying to get any ideas from experienced people.