The development of reusable dual-purpose nanocomposite foams for catalytic and bactericidal water treatment is reported. Small non-aggregated silver nanoparticles were made using Intermatrix Synthesis inside a polyurethane foam, which was chosen as a suitable polymeric matrix due to its high chemical and mechanical stability and industrial applicability. The antibacterial activity of the obtained nanocomposites was evaluated against suspensions of Gram-negative bacteria (E. coli), showing ideal bactericidal features for being applied to water disinfection. The catalytic activity of nanocomposites was also evaluated through a model reaction carried out under flow conditions. The possibility of reusing the catalytic material was evaluated in 3 consecutive cycles and, for all of them, no significant loss of efficiency was found. Moreover, the leakage of the active species to the media was evaluated under accelerated ageing conditions (3 h in an ultrasonic bath) and a negligible amount of silver was found outside the matrix. The chemical stability of the as-prepared nanoparticles was also evaluated by XANES and any modification in the chemical structure of silver nanoparticles was detected, even after storing the samples for two years under dry conditions