On Oct 6, 1:35*pm, dpb wrote:
z wrote:

...

well, i got my hose bibs hooked up to underground soaker hoses, and
that's most definitely vacuum breaker territory for me.

But do you frequently somehow manage to have lower pressure on the
upstream side of those bibs? *Except in exceedingly rare events, it's
hard to conceive how that would be so. *And, of course, once the soaker
hoses are turned off there's nowhere for it to go, either.

Not that they're not a safety precaution that makes some sense for the
application, but I'm still having difficulty figuring out a real high
likelihood, high consequence scenario that would seem to justify a
mandate for them on all outside faucets.

We've got a significant number of feet of soaker hose and other outside
irrigation and livestock operations but somehow the postulated doomsday
scenario hasn't occurred in nearly 100 years of farm operation.

--

oh sure, the only way it could happen is if somebody turned off the
mains, and opened a tap downstairs, and one of the hose bibs did
indeed allow inward suction when it was shut off. but that's not a
completely impossible state of affairs. rare, yes, and something i
myself would probably not do, but the effort involved in remediating
the risk wouldn't seem to be too high with respect to the degree of
risk and the pain in the ass represented by trying to fix the
situation if it happened.