Civil & Construction

OSD vs Retention: Understanding Stormwater Requirements

On-site detention and retention are related but serve different purposes.

October 13, 2026 · RCC Engineers
Aerial view of a residential subdivision development

OSD temporarily stores stormwater and releases it at a controlled rate to reduce peak discharge. Retention stores water for reuse, infiltration or other purposes and may reduce the total volume discharged from the site.

Some developments require one system, while others require a combination of both depending on council, planning and site requirements.