Using data from the Hubble Space Telescope (HST), Iyer et al. (2016) present a study of 19 hot-Jupiters. 10 of these hot-Jupiters show the presence of water vapour in their atmospheres, while the other 9 hot-Jupiters show no water vapour at all. The datasets for all 19 hot-Jupiters were combined to create one average overall spectrum. The overall spectrum agrees with models showing that cloud and haze layers are hiding the presence of water vapour deeper in the atmosphere. Such a finding means that hot-Jupiters did not form in an environment deprived of water.
Iyer et al. (2016), "A Characteristic Transmission Spectrum dominated by H2O applies to the majority of HST/WFC3 exoplanet observations", arXiv:1512.00151 [astro-ph.EP]