I installed two electric water valves from a furnace humidifier, one valve wired normally on for the normal water going into the faucet, the other valve wired normally off allowing water to feed a container full of red food coloring.
The switch only let one valve be energized at a time so water was either normal or red.
The other valve switched off, held back the water so the other valve could do it's thing, whichever "thing" it was.

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