A mix manifold comprising: a valve housing having a first fluid inlet, a second fluid inlet, a third fluid inlet, and a fluid outlet; a first fluid flowpath extending between the first fluid inlet and the fluid outlet a second fluid flowpath extending between the second fluid inlet and the fluid outlet; a third flowpath extending from the third fluid inlet, the third flowpath including a first branch extending to the first fluid flowpath and a second branch extending to the second fluid flowpath a first check valve disposed in the first fluid flowpath at a location downstream of an intersection between the first branch and the first fluid flowpath; a second check valve disposed in the second fluid flowpath at a location downstream of an intersection between the second branch and the second fluid flowpath; a first valve disposed in the first fluid flowpath and configured to control fluid flow between the first fluid inlet and the fluid outlet; a second valve disposed in the second fluid flowpath and configured to control fluid flow between the second fluid inlet and the fluid outlet; a third valve disposed in the third flowpath and configured to control fluid from the third fluid inlet to the first branch and the second branch; and a first handle extending between and linking the first valve and the second valve such that the first handle can simultaneously actuate the first valve and the second valve; a second handle connected to the third valve and configured to rotate a third valve member of the third valve; characterized in that, the second handle is configured to rotate the third valve member from a shut-off position to one of a first branch flush position and a second branch flush position, wherein the first handle interferes with rotation of the second handle to prevent the second handle from actuating the third valve to direct flow from the third inlet to the first branch or the second branch when the first valve and the second valve are open; and wherein the second handle interferes with movement of the first handle to prevent the first handle from actuating the first valve and the second valve when the third valve is positioned to direct flow to the first branch or the second branch. a valve housing having a first fluid inlet, a second fluid inlet, a third fluid inlet, and a fluid outlet; a first fluid flowpath extending between the first fluid inlet and the fluid outlet a second fluid flowpath extending between the second fluid inlet and the fluid outlet; a third flowpath extending from the third fluid inlet, the third flowpath including a first branch extending to the first fluid flowpath and a second branch extending to the second fluid flowpath a first check valve disposed in the first fluid flowpath at a location downstream of an intersection between the first branch and the first fluid flowpath; a second check valve disposed in the second fluid flowpath at a location downstream of an intersection between the second branch and the second fluid flowpath; a first valve disposed in the first fluid flowpath and configured to control fluid flow between the first fluid inlet and the fluid outlet; a second valve disposed in the second fluid flowpath and configured to control fluid flow between the second fluid inlet and the fluid outlet; a third valve disposed in the third flowpath and configured to control fluid from the third fluid inlet to the first branch and the second branch; and a first handle extending between and linking the first valve and the second valve such that the first handle can simultaneously actuate the first valve and the second valve; a second handle connected to the third valve and configured to rotate a third valve member of the third valve; wherein the first handle interferes with rotation of the second handle to prevent the second handle from actuating the third valve to direct flow from the third inlet to the first branch or the second branch when the first valve and the second valve are open; and wherein the second handle interferes with movement of the first handle to prevent the first handle from actuating the first valve and the second valve when the third valve is positioned to direct flow to the first branch or the second branch.