Mich. Admin. Code R. 325.1566
Rule 16. A campground owner shall ensure that a privy, outhouse, or portable privy that is used as a means of sewage disposal for a primitive campground has a watertight vault which has a minimum storage capacity of 500 gallons and which is vented above the roof. A campground owner shall ensure that the interior of the privy above the vault is constructed of smooth, easily cleanable, nonabsorbent materials and that all openings are screened. A campground owner shall ensure that a privy has a self-closing door. A campground owner shall ensure that a privy that has a capacity of more than 1 individual has privacy partitions. The department may approve proposals for a portable privy that has less than 500 gallons of storage capacity as part of the annual license to operate the campground if there is a service contract with a licensed septic tank cleaner and if the portable privy was pumped as needed during the previous year.
Mich. Admin. Code R. 325.1566