1. To properly turn off the water on this type of system first requires turning off the inside valve.

2. Open the outside valve.

3. Then open the small drain knob on the inside valve ( if there is one) to drain out any water remaining in the pipe.

This type of faucet actually closes on the inside of the house and is designed to avoid the freezing problem in the pipe.  The faucet should slope slightly down as it exits the house so that water in the faucet is drained away.  Close the inside valve if there is one.

Backflow Preventers are found on exterior faucets on newer homes.  These units are designed to prevent siphoning back into the home and contaminating the water supply.  They are readily available at hardware stores.  To release water trapped behind the BFP , press the button at the centre of the BFP or remove the unit temporarily for the draining process.