DeFACTO will enable and improve large-scale CO2 transport and injection by enhancing understanding of CO2 pipes and injection wells. DeFACTO is a vertical flow facility that enables the circulation of CO2 through a 90 meters deep U-tube loop (depicted in the figure). The loop is instrumented with over 100 high precision-fast response pressure and temperature sensors, allowing to measure pressure waves with a high degree of accuracy. The vertical flow loop is connected to a 139 meters long horizontal flow loop, located on top of the facility. The horizontal flow loop enables circulation of CO2 with precisely controlled parameters (contaminants, temperature, pressure, gas to liquid ratio). The CO2 is then circulated through the vertical loop where its behaviour can be analysed at different depths. Each tube in the U-loop can be isolated and pressurised or depressurised individually. The data collected help understanding when and how the CO2 freezes under depressurisation, cavitation phenomena, two-phase and transient flow behaviour, and ultimately assist engineers in the design of safer and more efficient CO2 transport and storage systems.  Experiments that can be performed through DeFACTO both with pure CO2 and with impurities (N2, up to 20% CH4).