The study is aimed at evaluating the influence of brine density data on the assessment of pumping requirements for geothermal installations. Five databases were compiled and compared, based on an evaluation of buoyancy effect in a producing well at the site of the Soultz-sous-Forets EGS/HDR project. The results show large discrepancies between the different references, which lead to severe inaccuracies in the evaluation of the buoyancy effect, and thus of the pumping requirements. It is therefore recommended that care be taken when using such databases, in particular when determining the size of the pumping systems. It is also recommended that new measurements of brine densities be carried out, focussing specifically on geothermal conditions. (c) 2006 CNR. Published by Elsevier Ltd. All rights reserved.