In this research farmers’ stated preferences towards water markets are analysed. The research aims to underline determinants of farmers’ attitudes towards allocation trading considering two water availability scenarios: average and drought year. A survey with 241 farmers in Guadalquivir and Almeria basins is used. Determinants of monetary value of water traded are analysed by means of Heckman’s two-steps model. Results indicate that participation increases when farmers belong to innovative type, have agricultural training and cultivate higher crops value. Additionally, low water supply guarantee and appropriate information on seasonal water availability increase probability of participation.