Rainwater management

[8] The Combined Sewer System (CSS) collects rainwater runoff, domestic sewage and industrial wastewater into a single pipe.

Combined sewer overflows (CSOs) contain untreated or partially treated human and industrial waste, toxic materials and debris, and rainwater.

The implementation of gray infrastructure, such as upgrading drainage networks, storage facilities or pumping stations with large diameter pipes, is critical to drain rainwater from urban catchments, while most green infrastructure handles the storage and infiltration of rainwater and drainage of gray infrastructure[8] Constructed wetlands for sewer overflows treatment are currently an effective and less costly option to prevent untreated wastewater from overflowing from polluted natural water bodies, and constructed wetlands that act as retention ponds during the rainy season can collect and treat rainwater due to their natural purification function, and produce high quality water for reuse after treatment by constructed wetlands with aeration system and soils infiltration system.

[14] Low-impact development (LID) refers to systems and practices that use or mimic natural processes that result in the infiltration, evapotranspiration or use of stormwater in order to protect water quality and associated aquatic habitat.

[15] Low-impact development (LID) practices provide more sustainable solutions than traditional piping and storm ponds in rainwater management.

[18] These methods create and restore green space and reduce the impact of built-up areas at the site and regional scales, promoting the natural flow of water within an ecosystem or watershed.

[19] To enhance irrigation in dry conditions, earthen ridges were constructed to collect and prevent rainwater from flowing down the hillsides and slopes.