We have recently started to get a very definite H2S (hydrogen sulfide) smell from only the cold water (CW) side in one of the bathrooms. The smell is there immediately when the CW is turned on and disappears after about 5 seconds. There is absolutely no sulphur smell from the HW side of the same faucet. There is no evidence of the smell from any of the other outlets (CW or HW) in the house. The new smell is somewhat coincident with a new sink installation which included a changeout of the old copper supply legs to the flexible SS braided type. We draw from a driven well and have a water softener. The untreated water from an outside faucet has a slight iron smell (as it has for the last 32 years) but no H2S smell.
We have an inlet supply filter housing (whole house). Would it help to fill this with clorox bleach and run it through the offending fixture?
I had a similar situation where the family started buying bottled water after a new faucet installation.
No, it wasn't me.
Since the water was good everywhere else, I figured what could I lose?
I changed the flexible water connectors with the brand I like, and the bad taste went away, just like that.