In a shower with multiple shower heads or water sources, the shower controls will need to consist of a thermostatic or temperature control and separate volume controls. The thermostatic valve will control the temperature for the shower, while each volume control will provide the water and shut off for each water source.
Showers with multiple shower heads tend to increase water and energy consumption. To conserve hot water, use low-flow shower heads, such as aerating shower heads that mix air and water, emitting a lighter, misty spray. Or use laminar flow shower heads that form individual streams of water which minimize water flow while still maintaining the feel of normal water pressure. Before you begin installation, check for any environmental restrictions in your area regarding the installation of multiple shower heads in one shower.