Water sharing rules are a key component of water conservation. We evaluate an innovative scheme where water is shared between farmers according to physical irrigation efficiency. Measuring efficiency requires information exchange between farmers and the water manager, as well as a digital architecture to share these data. Relying on a Discrete Choice Experiment with 202 French farmers, we analyse their preferences for this architecture. We find that around half of them are likely to join such a scheme where information is collected and used by the manager to allocate water. But most farmers are reluctant to share automatically through a smart meter their water consumption data. However, they are less reluctant to the transmission of information on cropping patterns, if they remain in charge (as opposed to automatic transmission from satellite observations or link with administrative data).