I have a custom shower to plumb and the mixing valves and volume control valves are all 3/4" threaded fittings. I have 1/2" hot/cold supply coming in to feed the shower. I will be plumbing the shower for a shower head and hand held shower which are both 1/2" threaded fittings. My question is should I run the piping between the mixing valve, volume controls and outlets in 3/4" pipe or should I reduce it to 1/2" out of the 3/4" fittings? Make sense?

3/4" means 3/4 NPT, not 3/4 copper tubing.

1/2" copper will be fine.

It should depend on your shower head, are you using one of those high flow rain shower heads? (Mine uses 10 .5GPM) and You need a Big water line and a Big water heater or an on demand water heater.

No its just a 2.5 GPM shower head. Will it hurt to run 3/4" pipe? Or does it not really matter.

John... how come you are not running full size 3/4" hot and cold copper tubing to this valve?

Then run 3/4" to volume control... then purchse a 3/4" shower head.. Just wondering here?

Seems you spent the money on increased volume control and mixing valve... why not get the higher volume out your shower head?

What size is your water heater?

Get back to me when you can... MARK

Just figured it was standard plumbing pipe sizes. The shower head and handheld are only 2.5 GPM. I'm not looking to get a huge amount of flow... I'm on a residential well. THe water heater isn't in yet but will probably be a 40 or 50 gallon. THe fixtures I like just happened to be 3/4" I was also told you will get better flow out of a 3/4" valve even if you only have 1/2" pipe running to it.