Backwater Valves

All new single, semi detached, row house and townhome dwelling units in the City of Ottawa require the installation of backwater valves (BWVs) on sanitary service laterals (sanitary building drains). 

The requirement for additional protection against sanitary sewer back-ups (back flooding) was introduced after many homes to experienced basement backups due to surcharging of sewer systems during significant rainfall events. A comprehensive review of storm and sanitary service BWVs was undertaken at the request of City Council. Report ACS2010-ICS-INF-006, item 2, approved by Council, which recommended expanding the Installation of BWVs by amending the sewer design guidelines per Technical Bulletin ISD-2010-1to include mandatory installation of BWVs on sanitary services for new home construction.

Development Information Officers

If you require the services of a Development Information Officer, please call 613-580-2424, ext. 23434 or

Approximate cost

Refer to Applicable Fees

Approximate timeline

Approximate Timeline based on City Council approved enhanced service level:

  • House – First review 5 business days

Your Building Inspector must confirm that a normally open BWV is installed on the Sanitary Building Drain for each dwelling unit in accordance with Ontario Building Code, Division B, section and the referenced CAN/CSA standards. The BWV must be located within the dwelling unit and accessible for inspection and maintenance purposes. Where applicable, the inspection of the sanitary BWV installation may be combined with the existing inspection practice for the storm BWV which occurs at underground plumbing rough-in and final interior inspection stages.

The permit plans and specifications must be on site and made available to the Building Inspector at the time of inspection. To ensure the availability of a Building Inspector, you should book your inspection 48 hours in advance. The Building Inspector name and phone number is identified on the building permit.

Building Code Service counters are open for personal services by appointment only. This includes the submission of permit applications, payment of fees and the issuance of permits. 

There are various methods for submitting applications.

Application Forms: Application for a Permit to Construct or Demolish