Sounds normal with gusty winds. The wind passing over the vent may causeThis may sound odd, but here it goes...
We have three toilets in our townhouse. For the past day or so, I have
noticed that the water in each toilet bowl appears to be moving quite a
bit. It looks like it's pulsing at times. Over the course of a few
hours, the water levels in the bowls are decreasing.
The only thing that seems to coincide with this is that it is
extraordinarily windy outside. I'm wondering if the wind is somehow
getting down the vent, causing the pulsing, and pulling water out of
the bowl past the trap. Does that sound nuts or plausible?
If I'm way off base, what else may cause this? BTW, the house is only
three months old.
a venturi effect, which will vary in pressure quite a bit. The house
pressure is relatively unchanged so the level of the water shows the
difference in pressure.