Why would water blow out of toilet bowl?

[FLBiker]

I tried googling this, but I didn't have any luck.  Today, I noticed on both of our toilets (we live in a two storey detached house, one toilet on each floor) had a lot of water inside the lids and on the seat -- it seems as if something blew the water up out of the bowl, splashing the lid.  And when I flushed the downstairs one, it sounded a bit weird (as if there were air in the pipes).  Yesterday, I saw a truck in my neighborhood that seemed to be doing something sewer related.  I'm not sure if they came back today.

Has anyone encountered this before?  Is it something to be concerned about?  I checked the basement and under the sinks and everything seems find plumbing-wise.

Thanks!

[Sanitary Stache]

Sewer main work is a good explanation for this.

Unclogging a blockage in a sewer pipe can blow water/air back up the drain pipes. This is typically done with a hose shoved down the sewer, sometimes accompanied by a vacuum.  Ask you neighbors if they experienced any similar blow outs and call your local sewer department to see what work they were doing. 

When new sewer is being installed the pipes are tested with air.  Once on a job the contractors somehow forgot to disconnect a sewer connection before air testing and destroyed someone's bathroom.  It was a significant claim the homeowner made.

Toilets can gurgle if the house plumbing isn't vented adequately, which could possibly result in some minimal splashing, but gurgling due to poor venting would be a regular occurrence when other water was running in the house.  (I get this in a downstairs toilet when a bathtub is draining).

[FLBiker]

Thank you, sounds good!  The sewer work I saw yesterday was by some new construction, so perhaps they were testing with air.  I'll check in with a neighbor or two.

[big_owl]

Eating taco bell again, eh?