I believe building defects period is 7 years.
But it would be hard to attribute a burst pipe as a building defect. Pipes burst all the time for any and no reason.
And who are you going to point the finger at – the builder; the plumber; the pipe manufacturer?
And you,re going to have to convince the OC to take up your case, because you as an individual can’t take the action. Are the OC going to stump up the money to fight this action when the outcome is questionable.
I can see that you are not pleased with paying for this incident. Your best bet may be to claim on your lot contents insurance, as generally insurance policies cover burst pipes.