In the water diffusion over a membrane activity, what substance was actually able to pass through the membrane?

In the water diffusion over a membrane activity, the membrane that is used is semipermeable. This means that the membrane allows substances with molecules smaller than the pore size to pass through while it restricts those that have larger sizes. 

The substance that is able to pass through the membrane is water and the solutes having particle size of smaller than pore size.