Flushing. Units are available with a flush valve, a high-level cistern or a low-level cistern. A flush valve needs an adequate mains supply and pressure; a cistern flushes from its stored volume. Match the flush inlet, rear or top entry, to the pipework.
Layout. Combination units are specified with the hopper or wash basin on the left or right; confirm the handing against the room layout. A fold-up bucket grid supports buckets over the hopper.
Space. Standalone hoppers suit smaller rooms. Combination units from 1200 to 1830 mm combine disposal and handwashing in one fixture.