This study evaluated wastewaters reuse in the production of perennial crops Arundo donax and Miscanthus x giganteus. The trials were conducted in pots under controlled conditions, with different water regimes (950, 475 and 238 mm) in two growing cycles. The results indicated that irrigation with wastewaters did not affect biomass productivity but the amount of irrigation did. Yet, biomass obtained from pots irrigated with wastewaters presented higher levels of ash and nitrogen content than biomass from control pots. The soil-plant system retained over 90 % of pollutant load resulting in wastewater depuration. Furthermore, the produced biomass can be economically valorized for energy or biomaterials, once irrigation with wastewater did not influence the contents in fiber and the calorific value. Still, the higher ash and nitrogen contents in the biomass can be detrimental especially when biomass is for combustion purposes.