Exterior Plumbing Permit

How Do I Apply? 

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

When is an Exterior Plumbing Permit Required?

An exterior plumbing permit is required for any sewer installation or repair, water service, or lawn sprinkler installation.

Types of Exterior Plumbing Permits

  • Lawn Sprinkler
  • Sewer Install/Repair
  • Water Service

What Will I Need to Submit?

  • For sewer installations and repairs or water service permits, no additional information beyond the permit application is required. 
  • Lawn sprinkler installations require a backflow report to be submitted by the plumbing installer doing the work, before the final inspection.

Fees & Plan Review

Building Permit Fees (PDF)

For exterior plumbing projects, we can do same day permits. When the permit is ready, you will be notified via email that the permit is ready for pick up as well as the final amount of the permit 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.

Things to Know

The most important aspect of a plumbing code is the protection of the potable water system. History is filled with local and widespread occurrences of sickness and disease caused by not safeguarding the drinking water supply. Many lawn care companies are now using lawn irrigation systems to spread lawn chemicals via a connection to a sprinkler head; for this, a reduced pressure principle backflow device is required.

Exterior Backflow Devices - Underground water connections require a curb stop from the water service to the backflow device. Drain or bleed valves are prohibited for underground water connections from the water service to the back flow device. A tee fitting with a brass cap is recommended on the water service side of the backflow device along with a union below grade to drain and winterize the system. An inspection is required prior to backfilling. Insulated enclosures are permitted to protect backflow devices.

The backflow device must be installed a minimum of 12 inches off the floor to a height of not more than 5 feet above the floor.

Interior Backflow Installations
- A clearance of 12 inches shall be maintained around the backflow device. If a hose bib is used to drain the irrigation system, it must be equipped with a vacuum breaker.


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