Rooftop downspouts are directed to vegetated areas rather than to impervious driveways, gutters and eventually into waterways.
Benefits & Problems Addressed
Reduced pressure on sewer systems: On-site capture reduces the amount of rainwater that must be managed by sewer systems and eventually drained into waterways.
Reduced pressure on receving waterways: Rooftop runoff is treated and handled on an individual building site, reducing the amount of polluted runoff making its way into streams and lakes.
Inexpensive stormwater fix: Modifying downspouts to vegetative areas rather than a driveway is typically an inexpensive procedure compared to other larger scale management practices.
Tips & Techniques
Vegetated receiving areas: Typical receiving areas for disconnected roof runoff include lawns, gardens, and other existing landscaping such as shrubs.
Soil & landscaping considerations: Soil amendments can be used to increase soil permeability if necessary.
Hot Buttons: Downspouts must discharge into suitable areas away from foundations or neighboring property.
Example
Portland OR US Downspout Disconnection Program
Toronto Downspout Disconnect Instructional Video
Water Environment Research Foundation Livable Communities Toolbox