Lawn Sprinklers/RPZ Backflow Preventer Permit

A building permit is required for the installation of a lawn sprinkler system.

The City of Naperville, in compliance with State of Illinois law, requires that all sprinkler systems include an RPZ (also called a backflow preventer). The RPZ is a check valve that prevents impurities, such as insecticides or animal wastes, from invading a home’s potable water system. This valve is crucial to maintaining the purity of a home’s drinking water and the safety of the community’s drinking water supply.

The City of Naperville has adopted a Cross-Connection Control Program. This program requires that all RPZs be tested when first installed and then annually thereafter. Upon installation, the owner must have the RPZ tested by a qualified, independent inspector and registered with BSI Online (bsionline@backflow.com). The City will verify the registration at the time of the final inspection.

If any portion of the sprinkler system is to be located within the public right-of-way/parkway, a Right-of-Way Encroachment License Agreement (PDF) must be completed and submitted along with the permit application.

To apply for a lawn sprinkler/RPZ permit, please visit the City of Naperville Permitting, Plans and Licensing Portal. The Permitting, Plans and Licensing Portal gathers all of the information needed to apply, pay for, and manage permits in one convenient place. It is designed for use on a desktop/laptop computer.

For details on the permitting process, including submittal, reviews, fees and issuance, visit the Building Permits page.