Table of Contents Storm Drainage (Runoff)

Storm Drainage (Runoff)

Drainage is a critical requirement for every subdivision. Inadequate drainage can lead to flooding , resulting in erosion, loss of stability or in property damage.  In addition, subdivisions that are not properly drained can result in damage to highways both in and downstream from the subdivision, resulting in a public safety hazard.

Storm water must be considered both in the subdivision and outside of it. The applicant may be required to have a drainage study or design prepared by a Professional Engineer or hydrologist. Drainage should be carried to a natural outfall or approved storm drain capable of carrying the additional flow.

Storm drainage requirements are developed and maintained by the Construction and Maintenance Branch.  The design guidelines are contained in the Hydraulics Manual, which is also in the most recent edition of the TAC Guide. Storm drainage systems should be certified for construction and location and designed by a registered hydrologist.

Section 86(1)(c)(iv) of the Land Title Act permits the Provincial Approving Officer to refuse subdivisions if the land has inadequate drainage installations.  A local government may regulate drainage for subdivisions by a Subdivision Servicing Bylaw.  The Ministry of Transportation and Infrastructure specifies drainage requirements for highways.

This guide is a living document; it is subject to change without notice. Please check the Rural Subdivisions Website ( to make sure your version is sufficiently current.