Do you have the water pressure and enough hot water to be able to run 4 fixtures at once? 10 gallons per minute is a pretty serious flow rate and will need a gigantic hot water heater even if you have enough pressure. With a 50 gallon heater, that's about a 5 minute shower before things start to cool off from cold water filling up the tank.

4 at once would be a very rare occurence, I was just thinking it would be nice to operate that way once in a blue moon. Typically, it would be run with one, but on occasion two. Two parents and two children. Recommendations for diverter set up? Thanks!

Valves per head on the output of a diverter.

You have to size the entire construction for the simultaneous use of all 4. That means that your water supply will have to be able to supply that 20 gallons per minute as well as your drain must be upsized to carry that away. There's no point in planning something that cannot be used due to insufficient infrastructure to support it.

Then and only then should you be looking at which trim and valves to use.

My suggestion would be to eliminate one of the shower heads in favor of using the hand held mounted on a bracket as that shower head. That will give you only 3 outlets, which will reduce the requirement for water supply and drain and allow you to use a fairly standard 3 way diverter valve available from most manufacturers. You will still need the thermostatic control valve and volume control valves to set temperature and volume. I highly recommend Kohler for novices to planning a multiple use shower as they have an on site planner to help you add up all of the needed valves and trim. If you are still having difficulty putting it all together, then visit a local plumbing supply house and have them put the package together for you. Expect to spend about 1-2K on shower plumbing alone, and that doesn't include the labor to install all of that.

Doing it right ain't cheap, either from the needed infrastructure, the ongoing costs to heat that much water, or the ecological costs of that much water down the drain.

Live_wire_Oak - can I asked a follow on question? I apologize I have not yet scoured the bathroom forum as I have the kitchen forum, as I am just beginning the selections for bathrooms.

I am realizing reviewing the initial estimate from a plumbing supplier that our current master shower set up is coming in at 2K before plumbing expenses! My trim kits are part of it, but only $500. Can you explain the necessity/preference for a separate thermostatic control valve and volume control valves? I can appreciate the features they seem to provide but is my former one lever controlling volume and temperature (whatever it would be called) completely passe and is it a mistake to cut back in this area? We are in the middle of a significant whole house remodeling and certain want to do it "right" and are in the top half of better for most of our choice, but not the top of the line � we try to make value decisions, especially given the scope of what we are spending.

You thoughts greatly appreciated.

I agree with live_wire_oak on reducing to 3 fixtures & allowing the handshower to be the 2nd shower head. We have that setup--1 regular raincan shower head, 1 handshower on a slide bar & 1 overhead raincan. We can run each one individually, any combination of 2 or all 3 at once. We have the Delta Lockwood with diverter. I am pretty sure it was discontinued end of 2011 & just about every showroom that carried Delta we went in had one on display--you could get a great deal like we did by buying the floor model. There's a link to the Lockwood shower system below as well as a pic of our setup.

I can comment of the thermostatic control--it's nice to have, but not a necessity. Often, if you're dealing with a multiple fixture shower setup, it tends to be pretty standard. Hope this helps!

Here is a link that might be useful: Delta Lockwood