We are installing body sprays in a shower and I am concerned about the drain capacity. The shower control valve can supply 9 gpm @ 90 psi. The city reports the supply is normally at 65 to 80 psi static pressure. Drain is a 2" pvc line assuming properly installed.
One drain at 2" should be able to handle it - just don't stand on the drain cover for long! My tub drain is 1.5", and on full-blast, the tub drains faster than the incoming water...a 2" drain is a lot bigger in area/volume. If you're really worried, they do make 3" drains, or you could put two 2" ones in or a linear drain, but ensure the underneath plumbing is big enough, otherwise, it won't make any difference.
Important note - I'm not a pro
Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013