Den wrote:

Los Angeles, city sewer.

Since you reported that no water was being used/flushed at the
time, it had to be caused by a disturbance in the city sewer.
Assuming this is a single-family residence (one floor/slab?),
a momentary overload of the street sewer can back up into the
house lateral line. As the backup progresses toward the house,
it forces air ahead of it. Normally, that air simply goes up
the stack vent. But if the backup goes far enough it can flood
the house sewer to the point where the vent is ineffective.
Then the air is forced out of fixtures, such as toilets and sinks
which may not have separate vent connections. As the flooding
recedes, it will siphon water out of traps which are not protected
by proper venting.

A blocked vent *could* make this situation worse, but you would
expect to hear gurgling at other times (such as when toilets are
flushed).

Ask neighbors if they experienced the same thing at the time or
see what answers the city has chuckle.
Jim



"Speedy Jim" wrote in message ...
Den wrote:

Group:

Had a really curious situation that I've never encountered before. This
morning for about five minutes all of my sinks and toilets started
violently
'gluging' and 'burping'. The water in the toilet pans started splashing
around, bubbling a and emptied. It sounded a bit like whole-house
indigestion! Any ideas what it was and how to prevent it?

Cheers

Den

Where are you located and is this a city sewer system or septic??
Jim