THE GREEN WALL OF FERLA The innovative water treatment and recovery system Welcome to the website of the Green Wall of Ferla, an innovative system designed to collect, treat and reuse the greywater of the Istituto Comprensivo Statale Valle dell’Anapo in the Municipality of Ferla, in Sicily. The system, built as part of the international project “Nature Based Solutions for Domestic Water Reuse in Mediterranean Countries” (Nawamed) has been called Wall2Water (W2W).