Toilets and sinks erupted!

I have a commercial building with 7 toilets and 7 sinks (no showers or other connections) on a single sewer line, which runs under the cement slab building to the street. The furthest sink is about 150 feet from the middle of the street, where I presume my line connects to the main sewer.

Last night, sometime between 6:00 P.M. 8:00 A.M., and with the building empty (all closed businesses, no people in the building), all the toilets and sinks erupted with some kind of grey, gooey, soapy, greasey mess. This is not normal sewage. Very little smell, and appearantly a residue of some kind from somewhere, but it did not come from my building.

My question is: What could cause this? It seems to me it would take quite a bit of back pressure in the sewer line to cause these to all back up like this, and they backed up with force, sending this stuff flying all over the bathrooms.

The city sewer department came out and inspected their line and found nothing. I am having my line roto-rooted out just to make sure there is not a problem there.

Any ideas or comments? I am clueless about how or what happened.

Unless there are occupied spaces on floors above that could have drained down, Storm water drains tied into your sanitary sewer with a rain storm occurring, or, equipment that automatically operates sending water to a drain. It would have to have been a city sewer problem.

You are now the detective on the case!

I had this happen in my home a couple of times. Seems my sewer line dumps into a manhole in the main sewer. There is a KFC up the street from me using the same main sewer line. Their grease trap failed and the ensuing grease formed a ball when it got into that manhole. The ball plugged the outlet of the manhole and the water backed up into my basement. The city had to pay for the clean up, and after it happened a second time, they have the main line on a regular and frequent check. I think they got on the KFC pretty heavy too. Your mess sound like mine on a larger scale. It seemed to be mostly gray water and not lots of smelly stuff.

one word: Poltergeist!

Trucks like on the following links blast water into drains to clean them. Someone have their drain cleaned nearby? City might have done this too, but might not want to say they were out there...

Big vacuum/water jet truck...
http://www.robojet.ca/010~HOME/

Water jetting...
http://www.robojet.ca/020~DRAIN_SERVICES/020~Commercial/015~Water_Jetting/

Billy_Bob said:

Trucks like on the following links blast water into drains to clean them. Someone have their drain cleaned nearby? City might have done this too, but might not want to say they were out there...

Big vacuum/water jet truck...
http://www.robojet.ca/010~HOME/

Water jetting...
http://www.robojet.ca/020~DRAIN_SERVICES/020~Commercial/015~Water_Jetting/

Click to expand...

Expecially if it was a private contractor working through a manhole backwards up a lateral for the building next door and they picked the wrong one... Oops!