You could have a contaminated faucet tip (remove the aerator and drop it into a glass of bleach water), or the pigtails to the faucet may have some rubber in them that contributes to the odor; bacteria is the cause of the odor. You're right, the CPVC is not the cause.
Your softener or those disposable cartridges could be colonized by bacteria. What type of filters do you have and where are they?
Quality Water Associates