Operating Permits for Specialized Onsite Sewage Systems

Specialized on-site sewage systems require routine monitoring and maintenance to ensure they operate properly, and to prevent premature failure.

The Washtenaw County Regulation for the On-site Management, Treatment and Disposal of Wastewater requires an Operating Permit for sewage systems that utilize alternative technology; that are non-residential sewage systems with high design flows; or that are for food service operations that generate fats, oils and grease.

Owner Requirements

Owners of these systems must:

  1. Contract with a Certified Operation and Maintenance Provider (COMP). Together with the provider, you will determine the type of monitoring and maintenance that will work for your particular design.
  2. Complete and submit the Operational Plan for Alternative Residential or Commercial On-site Wastewater Treatment Systems to our office. Once the form has been submitted to our office, the owner of the system will be issued an Operating Permit. There is no fee or cost for this permit. Both the owner and the selected maintenance provider will be mailed a copy of the permit.

Operating Permit

The Operating Permit will contain the following information:

  • The type of system that is treating and disposing of sewage on the property.
  • The requirements for operating and maintaining the system.
  • Any conditions or property use limitations required for the successful operation of the sewage system.
  • An expiration date. The permit will expire 5 years after the issuance date.

Annual Inspection Report

The Certified Operation and Maintenance Provider (COMP) (PDF) that you contract with will perform any necessary maintenance of the system and will submit an annual operational inspection report to our office. This annual operational inspection report must be accompanied with the appropriate report review fee upon submittal. The COMP will be submitting these reports to our office on the owner’s behalf.

Our office will review the report and communicate back to the owner one of the following:

  1. The system is operating in full compliance with no immediate corrections needed.
  2. The system is in compliance, but there are repair or maintenance items that need to be corrected by the time of the next annual report.
  3. The system has significant operational / maintenance deficiencies that need prompt corrective action.
  4. The system is not in compliance with the Operating Permit.

Field Review

A representative from our office will conduct a field review of the system at least once during each 5-year operating permit cycle, and may also make site visits to confirm required corrective actions. In addition to the maintenance, there may be effluent sampling requirements on properties using alternative pre-treatment devices. Sampling requirements will be set forth on the Operating Permit or the annual letter from our office. Sampling frequency will be based on the type of technology utilized and the operational status of the system.


Permits will need to be renewed at the end of the 5-year cycle. Permits are assigned to the property owner, and are not transferable. If the residential property owner sells the home, they will not need to have an inspection on the sewage system, provided that the system is in compliance with the Operating Permit. The purchaser will be required to get an Operating Permit in their name prior to property transfer.