Several instruments in Indian astronomy used water as the basis for their operation. For example:
- āḍhaka (vessel of 50 palas)
- clepsydra / ghaṭikā-yantra - measured the time of one ghaṭi (~1/60th day)
Though not technically an instrument, water itself was used to level ground in preparation for the installation of astronomical insruments. See for example Lalla's Template:Ref-SiDhVr, and his example of preparing a śaṅku (gnomon). Nīlakaṇṭha's Manusyālayacandrikā has a similar śaṅku description.