  We briefly introduce the VLBI maser astrometric analysis of IRAS 18043-2116
and IRAS 18113-2503, two remarkable and unusual water fountains with
spectacular bipolar bow shocks in their high-speed collimated jet-driven
outflows. The 22 GHz H2O maser structures and velocities clearly show that the
jets are formed in very short-lived, episodic outbursts, which may indicate
episodic accretion in an underlying binary system.
