Verify that all outside faucets are equipped with an ASSE #1011 approved hose bibb vacuum breaker or an integrated vacuum breaker (ASSE #1019 or ASSE #1052 approved) that prevents anything connected to your hose from entering your water system.
Once this has been verified and an approved hose bibb vacuum breaker (HBVB) has been installed, please submit/upload a photo of the faucet with the approved ASSE #1011 device attached.
You can purchase these approved ASSE #1011 vacuum breakers and anti-frost hose bibb vacuum breakers at most retail hardware stores for approximately $10-$20. Make sure it has the ASSE #1011 certification symbol stamped on the vacuum breaker.