Observations of H_{2}O isotopologues of the extreme OH/IR star OH 26.5+0.6 show
that the star has an initial mass consistent with it being an intermediate-mass star. The HerschelHIFI spectra show clear detection of H_{2}^{16}O and H_{2}^{17}O while H_{2}^{18}O is missing, consistent with
the prediction of hot bottom burning which occurs in stars with an initial mass ≥ 5 M_{ʘ}. The
star is currently losing mass at a high rate of a few 10^{-4} M_{ʘ} yr^{-1} which is thought to commence
in the past ∼ 200 years. We present new ALMA CO J=3-2 image which show that this high
mass loss (superwind) region is compact, surrounded by extended shells of lower mass loss
