If a landlord did not put a backflow preventative device in the plumbing is this grounds for breaking lease?

Everytime it rains the plumbing backs up in my bathroom and floods it out into the hallway. I am an in a basement apartment that is new construction. He admitted to me that he did not put a backflow regulator in. Does that tell you it wasn't built on a permit? Wouldn't the city inspector require and check for a backflow regulator? In Illinois would this allow me to break my lease and recieve the return of security deposit? It's been going on since I moved on and he won't fix it. I've been there a month. My bathroom was recently flooded for a whole week because of a lot of rain.