This bowed string instrument takes the form of a “bowed psaltery,” similar to the one described here. What differentiates this instrument from other bowed psalteries is the shifting resonances caused by moving water in the metal resonator pan. The instrument is mounted in such a way that the player can rock it with one hand while bowing with the other; this keeps the water moving to create the shifting resonances.
The shifting water idea was first exploited in Richard Waters’ famous Waterphone. For another instrument with this feature, see here. In the sound clip, Psalt Water is joined by a rumba box.