Urgent ..Please help...

I am writing regarding a home in the Bay Area, CA.

My sister bought it NEW about 8 years ago.

There is a leak in the pipes (bath tub area) inside the walls and is
dripping to the first floor. This could be serious and cost a lot of
money to repair.

Can anyone pls tell me what is the warranty for for such pipe leaks ?

We tried recaulking the bath tub ...but it did not help.

Is the builder responsible for this ?

What is the law with respect to home builders and plumbing/leaks/
related warranties ? is it 10 years ?

In speaking with the HomeBuilders they brushed us off ...saying the
warranty is only a year or so.

Do we stand on legally strong grounds ?

Thanks
Rita