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.
My first house was in Wilton, NH. I was on town water at the end of the pipeline up a hill. The well for the whole town(pop 2700) was a hundred yards from the well for Monadnock Spring Water(same aquifer). However, by the time the water reached my house through the 100 year old cast iron pipes it was tainted with iron sediment. Therefore, after living there for awhile I installed a whole house sediment filter even though it was town water.
Monadock Spring Water sells millions of gallons/year.
http://www.monadnockspring.com/home.cfm