Total Value Wall is an innovative multidisciplinary green wall. This system functions as a full-fledged building envelope with many structural advantages (better thermal insulation, sound insulation, a positive influence on the life of the facade and a lower fire risk), visual advantages (more green in construction / green in the city) and environmental benefits (capturing particulate matter, retention of rainwater). What is new is that this green wall is also able to purify waste water into water for low-grade applications such as toilet flushing. In the project two demonstrations will take place to positively bring green walls to the attention of, among others, construction professionals and private individuals / residents of the city. Ghent University monitors water quality and carries out a cost-benefit analysis.