Odd Backflow Preventer

I went to use a hose faucet connection on the outside of my house today and the backflow preventor was leaking badly. I took the backflow preventor off and tried to hook my hose directly to the faucet but the faucet connection was to big(ie the house faucet fitting was greater than the 3/4" water hose connection fitting) I then went to Lowes and they diligently tried to help but ultimately told me that I had some non-standard backflow preventor on some crazy outside house faucet. So I'm stuck!!!! Has anyone else ever seen this problem. The faucet connection seems to be a fine thread and about an inch in diameter. It then converts to the standard 3/4" connection that you can attach a water hose too. Thanks everyone for whatever help you can give.



Fine threads on the left take a thread on back flow preventer on the right. The threads on the right fit a hose.

Many hose bibs are made that way so that you CANNOT just attach a hose. The vacuum breaker is designed and required most places to prevent you from sucking up polluted water from the hose that is left in a puddle, bucket, or who knows what. You'll likely need to get a replacement from the faucet manufacturer, or, replace the whole thing. If you're lucky, the local plumbing supply house may have one.

Your faucet has an "integral" vacuum breaker, and ONLY one from that same manufacturer will replace it. it is done that way so you CANNOT remove it and attach the hose directly to the faucet.