What does it indicate when water leaks from the plastic "cap" on the top of an outdoor anti-siphon, frost-free water bib. The water sprays out of the cap only when the faucet is opened (turned on)?

How is this part of the bib repaired, or must a new bib be installed?

Thank you.

gusk2935

That plastic cap will unscrew and you will see replaceable washers inside, do this only with your main supply shut off. It helps to buy a rebuild kit for your brand of bib.