I believe Fairfield also has a limit as to how many unrelated people a landlord can rent to, as in the case of renting to college kids. I believe it is either four or possibly even five but no more than that.
Most municipalities go by the number of bedrooms, two persons per bedroom, thus a 2 bedroom single family home is acceptable for up to four persons, a three bedroom house up to six persons, etc. Go to your City Hall Health Dept. and they will confirm if this is true or not.