I live 2 story house with 3 full bathrooms. In our masterbath whenever we turn on any one of the two sinks, there is a foul odor emitting form the drain for the first 10 to 20sec while the water is running. This will happen every time we use the sinks. It only happen in the master bath. What is the cause and how can I get rid of that sewer like odor?

I Believe That It Is The 'u' Shaped Section Of A Pipeline That Always Retains Some Water In It When Not In Use, Which Prevents Gases (odors) From Coming Through. Trace Line Back From Sink For This 'u' Section And See How It Might Be Connecting With Other Portions Of Your System.