Why are water pipes in Taman Sentosa, SS3 Petaling Jaya not changed?

Residents in Taman Sentosa has been questioning why is it that the water pipes in University Garden, SS5 and all the areas surrounding Taman Sentosa changed to new pipes, but Taman Sentosa in SS3 are still using over 30 years water pipes and still has not been changed despite this matter being brought up in the SS3 Resident Association many years ago?