Create two small hoses to connect the vacuum breakers to the splitter.
We hook up the pressure regulator directly to the splitter or create a hose to run the pressure regulator.
To use the system, we connect main water hose from the city water source to the pressure regulator. Then use the valves that are built into splitter to control where that water is flowing.
Using the vacuum breakers on not only the black tank side, but also on the city water side, there is no chance of water flowing backwards to the splitter. When we travel, both sides are shut off. When one is in use, the other is turned off. For black-tank-contaminated water to mix with drinking water, the water would have to fight gravity and be sucked back to the black-tank-flush connection. Then it would have to somehow bypass the vacuum breaker, go to the splitter and both valves would have to be open. We do think about what would happen if the valve on the black tank side was to fail. If that was to happen, water would be pumping into the black tank, via the black-tank-flush. Now, the chance of that valve failing in the splitter is extremely minimal, but the consequences are so great that we decided to double up and add a second valve.