Abstract Suction caissons have been used successfully in the offshore oil and gas industry since the 1980s and more recently in offshore wind developments. During installation, instrumentation data are collected, including pumping rate and suction inside the caisson. This paper presents a calculation approach for using installation data to back-analyse in situ sand properties. Combining an analytical solution for pore water flow into a caisson and a trust-region optimisation algorithm, it is shown how measured pumping rate, penetration rate, and suction inside the caisson can be used to estimate a profile of hydraulic conductivity, including anisotropy, for sands with relatively high hydraulic conductivity greater than $$10^{-6}$$ 10 - 6 m/s. The extent to which such an approach can be expected to be successful is tested through a set of synthetic demonstration cases, generated with a finite element model, in order to identify capabilities and limitations. It is observed that a reliable estimate of the hydraulic conductivity of layered soil can be obtained, in some cases including anisotropy. Knowledge resulting from such back-calculation as demonstrated herein can be valuable in post-installation assessments, for example for design verification, asset management, and lifetime extension analyses.