A careful experiment on Vesuvio has shown an anomalous mean kinetic energy, , excess in moderately supercooled bulk water. This energy excess has a clear signature in the shape of the proton momentum distribution n(p), showing a secondary maximum at high p. To tackle this issue we have recently measured [RB910370] and n(p) of deuteron in heavy water in supercooled (276 K) and stable liquid phases (292 K). The deuteron n(p) at both temperatures shows no secondary maximum, but while the at 292 K is very close to the deuteron zero point energy (ZPE), its value at 276 K exceeds the ZPE and scales as the square root of 2 with the measured for protons at the same temperature. Additional data are requirecd to complete the temperature dependence of for D2O, and establish the role and nature of quantum effects in bulk supercooled water.