You should have made demand sooner. Plumber would use statute of limitations as a defense. Contact a local construction lawyer to see if you have a case. Also, make sure plumber has assets on which you could attach. Best of luck.
I agree with my colleague.
Behar Intl. Counsel 619.234.5962 Kindly be advised that the answer above is only general in nature cannot be construed as legal advice, given that not enough facts are known. It is your responsibility to retain a lawyer to analyze the facts specific to your particular situation in order to give you specific advice. Specific answers will require cognizance of all pertinent facts about your case. Any answers offered on Avvo are of a general nature only, and are not meant to create an attorney-client relationship.
You'll need to sit with a local attorney to examine the facts and the dates and to ascertain whether your damages will substantiate litigation. As has been pointed out, the statute of limitations may be a problem for you here.
I may be guessing or not licensed in your state. No atty/client relationship exists. I earn my living collecting points for "helpful" answers.