Thank you for your response. I was incorrect about the letter. It is not an official class action suit that I have to “opt-in”. They are asking for my permission to allow them to do a visual inspection in anticipation of a class-action suit.

The plumbing will definitely be in the thousands because it will require breaking up concrete (foundation?) with removal and replacement of new pipes. I have already called a drain cleaning service 2x to clear blockages. I have not had the lines scoped by a plumber to determine the exact cause of the blockages, but I have spoke with the neighbors and they suffer from the same problems.

I can contact the law firm and ask for clarification. What questions should I ask from them?