Plumbing, codes and procedures question?

I have a 1 story slab foundation house with 2 full baths. I live in the state of Alabama. The house was built in 2005. This morning I awoke to the sound of the toilets and tubs gurgling so I ran into the bathroom to see what was going on. Not water but sewage and waste of every kind rapidly rose and over flowed the toilets in both bathrooms filling the floor about an inch high then moved to my master closet and filled it and then went under the wall into my kitchen. I looked outside to see if any work was being done and I see the water department doing work about 3 houses down so I ran down the road and told a guy: "hey, do you know you're flooding peoples houses!" he said: "no, I didn't know anything about that" and later he said: "apparently you're the only one". I asked him what they were doing and he said a main pipe is clogged and we are trying to remove the blockage. I said: "well stop because you're ruining my house", so he asked me if I had a clean-out valve and where it might be and I said that I had never seen one on my property. I had to call servpro to come extract the overflow and now my insurance is going to battle with the city. I am wanting to file a lawsuit against someone because somewhere or another there is negligence because my understanding is this should not have happened. My questions are: 1. Arent there plumbing codes that dictate that a slab foundation house have a clean-out valve installed? If they are supposed to be installed, isn't the water department required to go and open clean-out valves so that if any sewage backs up it wont enter the house? Someone has to be at fault. Either my plumber for not installing one or the city for not checking for one first. Am I wrong with this thinking? Could someone please shed some light on what should have been done correctly? Information regarding any of this is greatly appreciated. Ok, I have talked to my insurance agent about this and my plumber and I will be talking with the water department soon. Turns out I have to file a claim at the water department with their insurance since my insurance wont cover any damage due to the fact that nothing is wrong on my property after he investigated. I asked my agent if I had any chance of receiving compensation for the damages and he said that he felt strongly that I would not encounter any problems. My plumber said that my house had probably at least 2 or 3 clean out valves but that it didn't matter anyway because the city does not do any work on anyone's home they only work on city property. The city is definitely at fault. I wont be suing but instead I will file the claim and go from there.