We use a discrete choice experiment with treatments to test if voluntary adoption of smart water meters by French farmers can be fostered by i) a collective conditional subsidy offered to farmers who adopt a smart meter only if the rate of adoption in their geographic area is sufficiently high, and ii) informational nudges. Using a sample of 1,272 farmers, we find contrasted results regarding our nudges, but we show that a conditional subsidy is an effective tool to foster adoption of smart meters. Interestingly, the willingness to pay for the conditional subsidy is equal to the subsidy amount and independent of the collective adoption threshold.