Your post inspired me to try to fix my silcocks because I too hate that whine.
I looked at the reviews for the vacuum breakers available at Home Depot and, interestingly, I’m not seeing any of the reviews mentioning whine/hum/noise. This leads me to assume that a new vacuum breaker will work fine and that the whine ends up happening when the VB ages (or if you get a defective unit).
, removed the old one using slip joint pliers, cleaned the threads, applied liquid pipe thread sealant, and screwed on the new one.
So far, no noise. Time will tell whether this is a short term solution or if it’ll last a reasonable number of years.
Note that some silcocks will have fine threads for a VB, some not. Make sure you get the right threading for your application.
If your dad already removed the VB then you don’t have this issue, but for others that might stumble on this conversation: Many VBs have a set screw in the side, which is screwed in and then broken off to prevent removal. Code often requires this. If yours is like that, you’ll need to drill out the set screw before you can take off the old one.
Just to make sure I have the situation correct:
You filled a tub that you don’t normally use with water (for an emergency supply). A day or so later, the ceiling and wall directly below the tub are soaked. You then drained the water. 20 minutes later you still hear dripping so wonder if it was the water in the tub or something else.
It’s possible the supply line to the tub faucet cracked or otherwise started leaking when you filled the tub, but it seems much more likely that the water in the tub was the source.
The drain was plugged when the leak occurred, so the drain lines themselves are unlikely to be the issue.
This is a fiberglass/plastic tub, right? I think the tub itself is slowly leaking either from a hairline crack or from around the outside edge of the drain. This leak slowly soaked and pooled on the floor beneath the tub. Now you are hearing that pooled water drip down.
I’d do a careful crawl of the tub and see if you can find anything that appears to be a crack.
I’d keep listening to the drip rate in the wall and see if it’s subsiding. Hopefully it is. At that point, it’s figuring out what, if anything you can do for mitigation. My first thought is heat and airflow in the room with soaked walls/ceilings.