1/2 vs 3/4 rough valves for shower (in California)

[MMNN]

Hello,
The thermostatic shower trim (and also sink wall-mounted faucet) I’m interested in come with the option for 1/2” or 3/4” NPT roughs/valves.

Since California requires max 1.8 GPM for showers plus only one-function at a time diverting, would the 1/2” rough be sufficient?
Is there any reason or benefit to getting the 3/4” rough?

Clarification would be appreciated—thank you and Happy Holidays!

 

[Terry]

1/2" easily handles two shower heads. So yes, 1/2" will work for you. Hansgrohe makes an I-Box with 3/4" inlets but it's rare that I've ever needed that sizing anyway. Most everything else out there comes 1/2" standard though Kohler also makes an optional 3/4" valve.