Can I put a double whirlpool bath in an upstairs bathroom?

check floor for support ,may need extra joist support ,and then lay over floor ply sheet ,to support legs, or 4 x2 screwed to legs and that will distribute weight of bath with water in,secure to walls as instructions bye and good luck

As Long as the flor joist aré 0.175 x 0.050 or over and like george said fix some timber under the legs to sprar the Loads on the bearing then it should've be fine just remember not to go to crazy with the bubble bath Best regards Gary