Water Supply Line

• The water supply line connects the water supply valve, on the wall behind the refrigerator to the water inlet valve, on the refrigerator itself. The tube is commonly made of copper or plastic. Some plastic lines have the connectors necessary to make a watertight connection at both valves permanently installed on the line; however, most plastic water lines require the installation of a compression nut and ferrule.
  
  

Compression Nut

• A compression nut must be installed on each end of the water supply line. The purpose of the compression nut is to provide the physical connection to the inlet or water supply valve. The compression nut slides over the end of the water supply line before the ferrule is inserted into the line. When installing the compression nut, ensure that the threading is toward the end of the water supply line.
  
  

Ferrule

• The ferrule must be made of brass; it provides structure to the plastic water line, as well as ensures the creation of a watertight seal. The ferrule is inserted into the end of the water line, which is compressed onto the ferrule using the compression nut when the line is installed.
  
  

Tightening the Nut

• It is important to ensure that you do not over-tighten the compression nut. To tighten the nut, rotate it clockwise by hand until tight. Once the nut is hand-tight, rotate it one-quarter of a turn using an adjustable wrench to complete the connection.