Catalysis of the reaction: 3,5-bisdiphospho-1D-myo-inositol 2,3,4,6-tetrakisphosphate + H2O = 3-diphospho-1D-myo-inositol 1,2,4,5,6-pentakisphosphate + phosphate + 2 H+.
inositol-3,5-bisdiphosphate-2,3,4,6-tetrakisphosphate 5-diphosphatase activity