Since the summer of 2022, the term ‘mega-basins’ has regularly made headlines. Supporters of these gigantic reservoirs see them as essential for the survival of agriculture in the face of repeated droughts. Conversely, their detractors condemn them as a ‘water hold-up’ by a productivist agricultural model and denounce them as an ecological aberration in this era of climate change. To better understand what is at stake in this ‘water war’ and go beyond the media images of confrontation, this film meets with opponents and irrigators in Vendée and Deux-Sèvres who are reflecting on the issue of access to water.