The similar poloidal patterns of divertor erosion andredeposition of the ASDEX Upgrade, DIII-D andJET tokamaks are examined by comparing hydrogen isotope retention at the surfacesof divertor tiles. The outer divertor strike point undergoes net erosion.The inner divertor is a region of net redeposition, with deuteriumco-deposition rates ∼20 μg m2 s-1 for all three devices; despite their differencesin geometry, size and plasma facing materials.This extrapolates to an unacceptably high tritium retention rate ina DT burning steady state tokamak.