Treated wastewater from constructed wetlands can be reused for flushing toilets, irrigation or any ather non potable water appication. The type of constructed wetland which is best suitable to deliver the required effluent quality and which is optimal under local conditions differs however.
In arid regions one generally tends to minimize evaporation which disqualifies surface flow constructed wetlands.
In some places land scarce so we have to make the footprint as small as possible which directs us to choose vertical flow constructed wetlands wity or without forced aeration or itermitted effluent discharge options.
On slopes gravity systems can possibly be used.
To make water available for reuse an external storage basin of tank for treated wastewater can be required or in some cases it is even possible to store a significant amount of water in a lower part of the constructed wetland itself.
These and many other design considerations will be made by Kilian Water when establishing the best suitable design of a biodigester and constructed wetland combination.