In forward osmosis, microgels can be used either in a dried state or as a concentrated aqueous dispersion. A sample with 25 mol% charged units achieved a balance between water flux and responsiveness. It reached fluxes of 2.84, 4.79 and 4.39 L·m−2·h−1 for the dried state, 40 wt% and 20 wt% dispersions, respectively, when tested with 5 g·L−1 brackish water. Furthermore, a 40 wt% dispersion drew 35 g·L−1 seawater at a flux of 1.36 L·m−2·h−1.