What is the Origin of the Water Vapour Signatures in Red Giant Stars?

We investigate the occurrence of water vapour signatures in a total of 10 red giants in the solar neighbourhood at mid-infrared wavelengths (12 pm). With the use of high resolution spectra from TEXES and synthesized spectra based on MARCS model atmospheres, we analyse the differences and discuss plausible causes. These include abundance adjustments, the addition of non-photospheric components (MOLspheres) and a different temperature profile.