Wild guess: maybe only the partial pressure[1] controls whether water will flow through the membrane, and the partial pressure of freshwater in this scenario is

Wild guess: maybe only the partial pressure[1] controls whether water will flow through the membrane, and the partial pressure of freshwater in this scenario is identical on both sides? [1]: https://en.wikipedia.org/wiki/Partial_pressure https://en.wikipedia.org/wiki/Partial_pressure