I want to attach a washing machine to my apartment's water supply.
The washing machine is simple and has one inlet and no internal heater. The apartment has both hot and cold water.
I plan to attach some extra pipes via T connectors after the cut-off valves which connect a faucet to the hot and cold pipes. I plan to mix the water using something like this two-inlet valve.
The question: do I need to add back flow / check valves to prevent the flow from hot pipe to cold, or vice versa? If I do, what kind of valves these should be?
Update: this device looks purpose-built for that.