Ariz. Admin. Code § 18-5-404
The minimum size lot approved by the Department will be governed largely by the area necessary for the safe accommodation of individual wells and/or sewage disposal systems. Where both the water supply and sewage disposal system must be developed on the same lot, the minimum size shall be at least one acre, excluding streets, alleys and other rights-of-way. Where water from a central system is provided for residential uses, the lot shall be sufficient to accommodate the sewage disposal system and provide for at least 100 percent expansion of the system based on a four-bedroom house within the bounds of the property allowing a minimum of five feet distance to the property lines. Where lots are zoned for commercial uses, the lot shall be sufficient to accommodate the sewage disposal system and provide for at least 100 percent expansion of the system within the bounds of the property allowing a minimum of five feet distance to the property lines.
Ariz. Admin. Code § R18-5-404