How to Install Water Supply Tubing for Your RO System

Start by turning off the water to avoid flooding your kitchen, and open a faucet to reduce the pressure in the pipes.
You can then safely unscrew your faucet's "cold water" hose.
Apply 10 to 15 wraps of Teflon tape clockwise to the inlet fitting and the tee fitting, place the rubber gasket inside the tee, and screw it onto the cold water inlet. Tighten firmly to prevent any leaks, making sure the hole in the tee faces an accessible direction, then screw the hose back onto the tee and tighten firmly.
Apply Teflon tape to the shutoff valve and screw it into the tee.
Unscrew the compression nut and slide it over the white tubing, connect this tubing to the valve by pushing it all the way in, and tighten the compression nut to hold it in place.

There you go: your water supply connection is installed! You can close the small shutoff valve and turn the main water supply back on.