Step 4 · Install Compression Fittings on Tubing
Take one of the cut ends of the water line. Slide a compression nut from your kit onto the tubing, ensuring the threaded side faces the end of the tube. After the nut, slide on the brass or plastic ferrule (also called a sleeve). The tapered end of the ferrule should face the end of the tube. Push the nut and ferrule about 1/2 inch down the tubing. Repeat this exact process on the other cut end of the water line. Both ends should now be prepped with a nut and a ferrule, ready to connect to the filter.