Erasmusgracht Amsterdam: horizontal helophyte filter for purifying wastewater and rainwater Source: atelier GROENBLAUW

Horizontal helophyte filter


  • Depth: 
    80 cm
  • Vegetation form: 
    helophytes and other water plants
  • Water: 2
  • Heat: 1
  • Biodiversity: 3
  • Urban agriculture: 1
  • Air quality: 1
  • Energy: 1
  • Multifunctional space usage: 3
  • Construction costs: 3
  • Maintenance/management: 2


Besides the system described above, filters also exist through which the wastewater passes horizontally. These filters do not require drainpipes or pumps and are therefore simpler in their construction. As such, this type of filter requires less maintenance than vertical filters. Its uses include treating polluted runoff from roads and car parks.

Schematic of a horizontal helophyte filter, rainwater from the road settles, helophyte filter purifies and clean water flows to surface water. Source: atelier GROENBLAUW