What are sponge city water retention modules?

Sponge City water storage modules, also commonly known as PP rainwater collection modules, are injection-molded from high-density polypropylene (PP).

Sponge City water storage modules, also commonly known as PP rainwater collection modules, are injection-molded from high-density polypropylene (PP). The individual units can be assembled together to form a prefabricated underground water storage tank without a concrete framework, serving as the core water storage components in Sponge City rainwater retention and collection systems.
These correspond to the black, porous plastic interlocking modules shown in the images of your product line.
Working Principle
The modules themselves feature a hollow frame structure; when multiple modules are joined together, they form a large hollow space. When the exterior of the reservoir is lined with an HDPE impermeable geomembrane, it creates a sealed reservoir for storing stormwater. Without the geomembrane, it functions as an infiltration basin, allowing stormwater to slowly seep down and replenish the groundwater.
Key Features
High Water Storage Efficiency
Effective water storage capacity exceeds 90%, with space utilization far surpassing that of traditional structures.
Lightweight and Quick to Install
The modules are lightweight and can be assembled manually without the need for large-scale concrete pouring equipment, resulting in a construction timeline significantly shorter than that of concrete reservoirs.
Excellent Compressive Strength
Made of modified polypropylene, the modules offer high compressive strength and can support soil cover and vehicular traffic (depending on the selected load rating), making them suitable for underground installation beneath green belts and parking lots.
Flexible Configuration
The length, width, and height of the reservoir can be flexibly adjusted according to site dimensions to accommodate irregularly shaped plots.
Durable and Long-Lasting
Resistant to acids and alkalis, corrosion-resistant, and resistant to algae growth; Service life of up to 50 years in a sealed underground environment; modules are removable, allowing for future modifications or relocation.
Environmentally Friendly and Recyclable
Raw materials are non-toxic, and discarded modules can be recycled and reused.
IV. Two Main Application Types
Rainwater Collection and Storage Tanks (with Geomembrane)
Collects and stores purified rainwater, which is later pumped out for use in landscaping irrigation, road washing, and landscape water replenishment.
Rainwater Infiltration and Retention Basins (without Geomembrane)
Rainwater is temporarily retained and slowly infiltrates the soil, reducing peak stormwater runoff and alleviating pressure on municipal drainage networks.
System Integration (Integrated with Your Complete Product Line)
Water Storage Modules ← HDPE Drainage Pipes ← Siphon Drainage Channels (Channel A + Tees and Crosses) ← Polymer Protective Drainage Profiles
Together, these components form a complete siphon rainwater collection system for garage rooftops and green spaces.
VI. Main Application Scenarios
Sponge City Construction Projects
Rainwater recovery and reuse in residential communities and underground parking garages
Rainwater storage and regulation in parks, green spaces, and plazas
Rainwater collection in industrial parks and on roads
Urban flooding prevention and runoff reduction projects