The importance of cold gas in the picture of galaxy evolution is well known, as is its role as a probe of recent environmental effects on galaxies. However, sensitivity limitations mean the extent to which environment impacts the gas-star formation cycle of galaxies remains unclear. With this talk I will show how we take full advantage of the powerful HI spectral stacking technique to overcome this obstacle and quantify the gas content for the entire gas-poor to -rich regime. This was accomplished using an the largest sample of HI and multi-wavelength information available (28,000 galaxies), selected according to stellar mass (M*>10^9 Msol) and redshift (0.02 <= z <= 0.05). I will present HI scaling relations with key structural, star formation and environmental metrics, using stacking to provide strong observational evidence of significant and systematic environment driven gas suppression across the group regime, well before galaxies enter the cluster. Furthermore, I will show that gas depletion is more closely associated to halo mass than local density and cannot be reproduced by starvation of the gas supply alone, invoking systematic ram-pressure stripping of the cold gas to explain this. Finally, I will show preliminary results highlighting the role of HI in regulating the correlation between stellar mass, star formation and gas-phase metal abundance known as the “fundamental" mass-metallicity relation.