On-site disposal of poorly treated household wastewater can be a significant source of pollution in ground and surface water.
NIWA has produced a set of practical guidelines for constructing wetlands that treat wastewater and septic tank effluents, using little or no energy or mechanisation. The guidelines outline how to build a simple horizontal subsurface-flow wetland, which is capable of achieving secondary treatment standards.
Constructed wetlands use robust natural treatment processes. Meaning they have longer residence times, can deal with fluctuations in usage and loading better than package treatment plants, and are less reliant on technical maintenance.
NIWA is also developing a suite of advanced wetland-based systems capable of achieving tertiary treatment standards. These systems will be particularly valuable for sensitive lake-side and coastal zones. Further information will be on our website as the development proceeds.