  Using the Atacama Pathfinder Experiment (APEX) telescope we have detected the
rotational ground-state transitions of ortho-ammonia and ortho-water toward the
redshift ~0.89 absorbing galaxy in the PKS 1830-211 gravitational lens system.
We discuss our observations in the context of recent space-borne data obtained
for these lines with the SWAS and Odin satellites toward Galactic sources. We
find commonalities, but also significant differences between the interstellar
media in a galaxy at intermediate redshift and in the Milky Way. Future
high-quality observations of the ground-state ammonia transition in PKS
1830-211, together with inversion line data, will lead to strong constraints on
the variation of the proton to electron mass ratio over the past 7.2 Gyr.
