Separate tub and shower share supply?

[Dmt78]

So I’m trying to figure out “best” way to run my supplies to a soaking tub and walk-in shower that are back to back in the same bathroom.

If I branch down from 3/4” trunk in joists above, could I use the same 3/4” branch to supply both the tub on the left of that wall and the shower to the right of that wall? Maybe tee off above the shower valve and come down to feed the tub?
I could use the other wall for shower too, but was just trying to keep trunk run as simple as possible. Thanks.

Flow rates are:
Shower — 1.6 gpm
Tub spout — 6.3 gpm
Tub handheld sprayer thing — 1.8 gpm

 

[John Gayewski]

Yes you can generally use one 3/4 to supply both

 

[Sponsor]

 

[Reach4]

If you don't do hot water recirculation, consider a separate 1/2 inch hot for the shower+lavatory to let hot water arrive about twice as fast.

 

[Dmt78]

If you don't do hot water recirculation, consider a separate 1/2 inch hot for the shower+lavatory to let hot water arrive about twice as fast.

Should I do 1/2 branch for hot and 3/4 for cold for both the tub and separate shower to share?

I also have double vanities in this bathroom that I was going to drop 3/4” hot/cold then split side to side 1/2” to each sink?

 

[Reach4]

I was thinking combined 3/4 for cold. Separate 3/4 for soaking tub. shower 1/2 for shower and lavatories, but maybe separate 1/2 for shower hot could be worthwhile. I am not a plumber.

For really fancy, separate 3/8 for both lavatories, or even each lavatory, but 3/8 costs more than 1/2. The point is to reduce the time, and hot water consumption, for hot to arrive in the absence of recirculation. So "best" can be measured by more than one way-- some cost/ease sensitivity vs pure performance, energy, and water consumption. Par is shared 3/4 for cold and shared 1/2 for hot, but speed in filling the soaker tub would suffer.

 

[Dmt78]

thanks Reach. I’ll probably do the separate 1/2” hot for shower. I’m trying to use as few fittings and materials, mainly to maximize flow.