Observations of H2O 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 Herschel-HIFI spectra show clear detection of H216O and H217O while H218O is missing, consistent with the prediction of hot bottom burning which occurs in stars with an initial mass ge 5 Mȯ. The star is currently losing mass at a high rate of a few 10-4 Mȯ 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.