Yesterday I had a plastic on/off valve from the wall to my toilet crack (defective), and caused substantial damage. I am questioning whether this type of valve should have been used by the builder. I have a home warranty and the company providing the warranty is questioning whether they are responsible or not.
You will never get a warranty company to admit they are liable. Depends on what they find the cause of the valve failure was. Was it kicked? I agree that they should cover it, but I am not an insurance company.
If you have never made a mistake, you haven't done much.