0.5 gpm faucet aerators are well suited for bathrooms and hand wash sinks. There is little noticeable difference in water flow between a 1.0 gpm needle flow aerator and the .5 gpm needle flow aerator.
Due to the low amount of water output, .5 gpm aerators are only available in spray flow.
Under Federal Law, faucets installed in public lavatories (exposed to walk-in traffic) must deliver a maximum flow of 0.5 gpm (ultra low flow spray). This flow rate standard applies to all of the US and Canada.