Among promising novel membrane materials for enhancing desalination performance, graphene has been realized as a high potential candidate due to its unique properties. However, large area graphene membrane, dominantly available through wet transfer and assistance of polymers, has inevitable features like defects, holes and cracks that could limit realistic prospects of industrial-scale production of desalination membranes. Here, using hole arrays in silicon as a secondary and a fine mesh grid as an initial support, we experimentally designed a mobile nanoporous graphene membrane with tunable salt rejection and water permeation by favourably limiting the undesired effects of defects and holes on the graphene. A model is also presented to support the experiments and give more insight into the possible superpositions (i.e. motifs) that occur by movements of graphene/grid over silicon hole arrays. Using the moveable assembly of graphene/grid/hole arrays and the consequent motifs, a range of high permeation (4.34 x 10(7)-5.90 x 10(7) Lm(-2) h(-1) bar(-1)) and NaCl rejection (58%-100%) values were obtained. The moveable assembly of graphene/grid on fixed silicon hole arrays opens possibilities of fabrication of scalable atomically thin membranes for water desalination and can be applied for many other separation purposes specifically ion selectivity and filtration of multivalent ions or larger molecules.