The middle atmospheric water vapor radiometer MIAWARA is located close to Bern in Zimmerwald (46.88° N, 7.46° E, 907 m) and is part of the Network for the Detection of Atmospheric Composition Change (NDACC). Initially built in the year 2002, a major upgrade of the instruments spectrometer allowed to continuously measure middle atmospheric water vapor since April 2007. Thenceforward to Mai 2018, a time series of more than 11 years has been gathered, that makes a first trend estimate possible. For the trend estimation, a robust multi-linear parametric trend model has been used. The trend model encompasses a linear term, a solar activity tracker, the El Niño–Southern Oscillation (ENSO) index, the quasi-biennial oscillation (QBO) as well as the annual and semi-annual oscillation. In the time period April 2007 to Mai 2018 we find a significant decline in water vapor by −0.6 ± 0.2 ppm decade −1 between 61 and 72 km. Below the stratopause level (~ 48 km) a smaller reduction of H 2 O of up to −0.3 ± 0.1 ppm decade −1 is detected.