The liner should prevent pollution of the groundwater with wastewater. The most commonly used barrier are plastic liners, such as EPDM rubber, high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE) and polyvinylchloride (PVC). The material should be UV- and frost resistant. Also the resistance against punctures by gravel, stones, roots and rhizomes is very important. The thickness usually varies between 0.5 - 2.0 mm.
A geotextile liner can be used to protect the plastic liner.
Horizontal Subsurface Flow CW's: Liner
Constructed Wetlands