Septic System Permit

How Do I Apply?

Please visit the Building Construction Permit section of our Citizenserve Citizen Access Portal to apply online.


When is a Septic System Permit Required?

There are several instances of when a septic system permit must be obtained. They include:
  • When a new septic system is being installed on a property
  • When major repairs to an existing system need to be made
  • Before a property with an existing septic system is sold
  • After a property with an existing septic system is sold

Types of Septic System Permits

  • Septic Installation (for new permits)
  • Septic Repair (for existing septic systems)
  • Septic Certification (for existing septic systems before a change in ownership)
  • Maintenance Agreement (for existing septic systems after a change in ownership)

Contractor Listing

To view a list of active drainlayers and third party inspectors that inspect private sewage systems and wells, visit our Citizenserve Citizen Access Portal and go to Reports at the top of the page, then choose Active Licensed Contractors from the available reports. To view a list of engineering firms that will design custom septic systems, click on our engineer list.

What Will I Need to Submit?

Contact St. Charles County's Wastewater Inspector at 636-949-7345 for more information.

Fees & Plan Review

Building Permit Fees (PDF)

  • Septic Installation: For a residential system, fee of $150 or 0.0073 of the system estimated cost, whichever is higher.
  • Septic Repair: For a commercial system, fee of $250 or 0.0073 of the system estimated cost, whichever is higher.
  • Septic Certification: Free
  • Maintenance Agreement: $75 one-time fee


At least one inspection will be required. When the permit is issued, the necessary inspections required will be listed on your permit card. At the inspector's discretion, some inspections may not be applicable to the particular permit in question. The inspector will note those inspections are "N/A" at a later date.

Inspections must be called into the office by 3 p.m. the business day prior to your requested inspection date. To schedule your inspection, call 636-949-7345. If it is necessary to cancel or change your inspection, please do so as soon as possible. Also, please remember to post your permit so that it is visible from the street.

Septic inspection information:
  • Layout and Design: The installer is required to stakeout the septic system, including the location of the tank, lateral lines, or drain field. A layout and design drawing must be submitted to the county code official prior to inspection, and it must be approved before a footing inspection will be allowed.
  • Septic Tank and Field: inspection done once the septic tank and drainage fields are installed, but not yet back-filled. 
  • Septic Final: Done after the septic tank aerator is wired and installed and finish grade on drainfield is seeded and strawed. (Finish grade, seed and straw is dependent on weather conditions.) This inspection must be completed AND approved BEFORE the final occupancy inspection will be allowed.


Please contact the St. Charles County Building and Code Enforcement Division at 636-949-7345 or