We present the results of 22 GHz H _ { 2 } O maser observations of a sample of 85 post-Asymptotic Giant Branch ( post-AGB ) candidate stars , selected on the basis of their OH 1612 MHz maser and far-infrared properties .
All sources were observed with the Tidbinbilla 70-m radio telescope and 21 detections were made .
86 GHz SiO Mopra observations of a subset of the sample are also presented .
Of the 21 H _ { 2 } O detections , 15 are from sources that are likely to be massive AGB stars and most of these show typical , regular H _ { 2 } O maser profiles .
In contrast , nearly all the detections of more evolved stars exhibited high-velocity H _ { 2 } O maser emission .
Of the five sources seen , v223 ( W43A , IRAS 18450 - 0148 ) is a well known ‘ water-fountain ’ source which belongs to a small group of post-AGB stars with highly collimated , high-velocity H _ { 2 } O maser emission .
A second source in our sample , v270 ( IRAS 18596 + 0315 ) , is also known to have high-velocity emission .
We report the discovery of similar emission from a further three sources , d46 ( IRAS 15445 - 5449 ) , d62 ( IRAS 15544 - 5332 ) and b292 ( IRAS 18043 - 2116 ) .
The source d46 is an evolved post-AGB star with highly unusual maser properties .
The H _ { 2 } O maser emission from d62 is probably associated with a massive star .
The source b292 is a young post-AGB star that is highly likely to be a water-fountain source , with masers detected over a velocity range of 210 km s ^ { -1 } .