Water stench in home water supply

How to disinfect and flush water pipes for bacteria

Hi, we are getting stench in water. This problem is only when we open the taps and shower. How do I flush and disinfect the pipeline at home? Any one who provides this service in chennai? I have taken sample from the inlet and there is no smell, it's only at the tap level. So was thinking I need to disinfect the pipelines Any help and guidance pls. Regards Gopal