Any such premises not connected with a sanitary sewer system shall be equipped with an adequate septic tank having a capacity of not less than five hundred (500) gallons for each seven (7) persons living or working in such place, and an additional seventy five (75) gallons for each person in excess of seven (7); provided, that the tank in any premises used for meeting purposes shall have a capacity of not less than one thousand five hundred (1,500) gallons. (1968 Code, sec. 53-102)