The IB120SS requires pressure from a water supply source. Residential water supply is typically between 40 and 80 PSI. The unit will typically operate correctly with pressure as low as 20 PSI. The intake valve on the unit itself simply opens and closes and allows water to pass thru the unit and into the ice maker tray. Performance issues, ice production quality, harvest times etc can be negatively impacted by low PSI.
Please note: The water supply connection on model IB120SS requires a 1/4" supply line. When selecting a supply line, or when selecting a water filter to be attached to your ice maker, please ensure they are for 1/4" connections. These supply lines / water filters are readily available at plumbing supply stores, Home Depot, Lowes, Amazon.com etc etc.