Rotten egg smell is from sulfur deposits in the bedrock.
I have lived in three different houses with drilled wells here in NH. They have all had hard water to some extent. Typically calcium and iron. My previous house’s water would turn the toilets/shower heads reddish brown until we installed an inline whole house sediment filter. I would change the filter every 3 months. It would be dark reddish brown like an old rusted car.
The current house has a radon problem. We installed a bubbler. It is about the size of a washing machine. All the water goes through it. I typically only drink the water that goes through the fridge filter.
I know (S), which is probably why it’s good for you. Good job on the filter for iron with air added, a lot of the softener companies milk that problem and install ion exchange systems which are totally unnecessary. My parents had one for the longest time, and they just needed air and filtration.
Even in an area with decent water you can goob it up if you mix pipe metals. I was monitoring dewatering on the Devils Slide tunnel out here a few years back. Everyone was pulling their hair out because the water from one bore would come out clear into the holding tank and then you could watch it cloud until the turbidity was over discharge limits. I asked around, and it turned out the driller/installer had run out of iron pipe midpoint and switched to galvanized. The coating was enough to prompt an electrochemical reaction that took iron from the ungalvanized into solution, and as soon as it reached the tank and aerated it would oxidize into a colloidal suspension. Filter after the air exposure fixed it, cost a couple hundred bucks.
So far, so good. :)