Herschel/HIFI observations of water from the intermediate mass protostar NGC 7129 FIRS 2 provide a powerful diagnostic of the physical
conditions in this star formation environment. Six spectral settings, covering four H_2^(16)O and two H_2^(18)O lines, were observed and all but one
H_2^(18)O line were detected. The four H_2
^(16)O lines discussed here share a similar morphology: a narrower, ≈6km s^(−1), component centered slightly
redward of the systemic velocity of NGC7129 FIRS 2 and a much broader, ≈25 km s^(−1) component centered blueward and likely associated
with powerful outflows. The narrower components are consistent with emission from water arising in the envelope around the intermediate
mass protostar, and the abundance of H_2O is constrained to ≈10^(−7) for the outer envelope. Additionally, the presence of a narrow self-absorption
component for the lowest energy lines is likely due to self-absorption from colder water in the outer envelope. The broader component, where the
H_2O/CO relative abundance is found to be ≈0.2, appears to be tracing the same energetic region that produces strong CO emission at high J
