On Sep 12, 12:20*am, Larry Fishel wrote:
On Tuesday, September 11, 2012 4:23:08 PM UTC-4, DerbyDad03 wrote:
Why would a clogged vent cause water to be sucked out of multiple
traps during the time we were at work?

By itself, it wouldn't, but it would "seal" your drain system and allow some other event downstream (maybe related to opening a manhole) to suck your traps, which shouldn't happen if the vent is NOT blocked...

I guess that's possible, but it would be a strange coincidence for
both the blockage and the downstream event to occur at the same time.

Since I've seen no other symptoms associated with a blocked vent, it
would have to have been a 1 - 2 punch on Monday.

I'll keep an eye on the situation and see if any "blocked vent"
symptoms become apparent.