  We report the first detection of a water megamaser in a radio-loud galaxy,
3C403. This object has been observed as part of a small sample of FRIIs with
evidence of nuclear obscuration. The isotropic luminosity of the maser is ~1200
L(sun). With a recessional velocity of cz ~ 17680 km/s it is the most distant
water maser so far reported. The line arises from the densest interstellar gas
component ever observed in a radio-loud galaxy. Two spectral features are
observed, likely bracketing the systemic velocity of the galaxy. These may
either arise from the tangentially seen parts of a nuclear accretion disk or
from dense warm gas interacting with the radio jets.
