Many disc-type post-asymptotic giant branch ( post-AGB ) stars are chemically peculiar , showing underabundances of refractory elements in their photospheres that correlate with condensation temperature . The aim of this paper is to investigate how accretion from a circumbinary disc can cause this phenomenon of depletion and how this impacts the evolution of post-AGB stars . We used the MESA code to evolve stars in the post-AGB phase , while including accretion of metal-poor gas . We compared the models to a sample of 58 observed disc-type post-AGB stars with chemical abundance data . For each of these stars , we estimated the luminosity and the mass using the Gaia distance . We modelled the accretion rate onto the binary from a viscously evolving disc for a range of initial accretion rates and disc masses . We find that large initial accretion rates ( \gtrsim 3 \times 10 ^ { -7 } M _ { \sun } /yr ) and large initial disc masses ( \sim 10 ^ { -2 } M _ { \sun } ) are needed to reproduce the observed depleted post-AGB stars . Based on these high accretion rates , the evolution timescale of post-AGB stars can be significantly extended by a factor between two and five . We distinguish depletion patterns that are unsaturated ( plateau profile ) from those that are saturated , and we expect that post-red giant branch ( post-RGB ) stars are much more likely to show an unsaturated abundance pattern compared to post-AGB stars . Finally , because of the slower evolution of the low-mass post-RGB stars , we find that these systems can become depleted at lower effective temperatures ( < 5000 K ) . We conclude that accretion from a circumbinary disc successfully accounts for the chemical peculiarity of post-AGB stars .