HSN code and rate

GST @ 12% - Power driven pumps primarily designed for handling water, namely, centrifugal pumps (horizontal and vertical), deep tube-well turbine pumps, submersible pumps, axial flow and mixed flow vertical pumps [8413]

GST @ 28% - all other pumps 

HS Code for Booster Pumps, which are not primerily designed to handle water would be 841330, with IGST @ 28%