We found black mold in the pitcher's cover and decided to throw it out.
However my main concern is the spread of the mold elsewhere in water line. Would the underneath water line would have been corrupted with this mold? How can I find out?
Does Samsung recommend me to replace the water lines including filter?
Mold usually appears with improper cleaning of the pitcher or defective filtration. Your local water supply may not be a pure as you think. Replace your water filter. I would also replace the water lines, as who wants to take the chance since you don't know the source of the mold? Mold spores are prolific and spread easily. You should also replace the lines between the filter and the water dispenser - this may require a professional, as it would appear it would involve some dismantling of the fridge.
Samsungparts.com may have the hoses, but water lines from your home's water source to the fridge are generally standard - it's the connector at the fridge end that would be an issue, if there is one. The connector nut is going to be kept anyway. Samsung parts should also have the pitcher replacement. You can call them if you can't find it on the website. The number is on the website.
Replacing the lines from the home connection to the fridge should be something you can do yourself, or if you want to pay a handyman (I don't think you need a plumber). As far as inside the fridge, I'd put in a service ticket with Samsung Service to find a qualified repair shop. Even if the fridge is not under warranty, you should still get someone who knows Samsung appliances.
You might not even have to replace the internal hose if there is a way to run bleach/disinfectant through it. Maybe just getting someone to flush it out would be sufficient. If you do find a replacement pitcher, make sure you remove the pitcher at least weekly and give it a thorough cleaning, including removing any rubber gaskets on the lid and cleaning underneath those and not replacing them til fully dried.
It could be that you won't need to replace the lines at all, the mold may have just been in the lid of your pitcher due to water sitting under the gaskets. This is the most common location of mold growth in vessels with gaskets, such as the lids of storage containers and water bottles. Most people think a simple rinse or washing with soap and water is sufficient, not realizing the seals must be removed to dry out any water that may have seeped underneath. Also all mold that is black, is not necessarily the genus known as "black mold".
