[banditpowdercoat]

The system only pushes waste water when the Hot water tap is ON. When the hot tap is off, no water can flow, the whole system is at an equal pressure. It can not flow Back to the hot water tank. This system needs a RO reservoir, because it only makes water when the hot tap is being used. Stop the flow of hot/waste water, and the RO unit shuts off.
Now, a real benifit of this is if you plumbed the waste water into the COLD water inlet into your hot water tank. And, had a large enough Res to suit your needs. Then, Any time the Hot is being used, the waste goes into the Hot water tank, and gets heated, Thus not wasting any water you just heated.