Biosphere II ran on (mostly) recycled and reclaimed water, and surely the tech of 100 years hence will have those problems mostly whipped.
We have them whipped now. There exists a matrix of polymers and 'secret stuff' that forms a sponge-like material that will absorb only water molecules from untreated sewage on one side and expels 100% pure H2O on the other side. It has no moving parts and requires only a minor temperature or pressure difference across the 'filter' to drive the process.
It was developed for NASA and is undergoing small-scale testing in Florida in preparation for the construction of giant reclaimation plants in China. They project over 50 years of operation with no maintenance to the filter.