We have well water, and no filter. Our water comes from an aquifer--a nice underground lake that has it's origins back in the days of glacial Lake Agazziz! It's wonderful water, except that our well was put in at 55 feet, and we do have some iron in our water. Most of our neighbors have 35 foot wells or even just sandpoints, and they have really good water, no iron. Even so, our water, iron and all, is still better tasting that any city or town water. Let me clarify--we don't have a lot of iron in our water--it stains the sink, toilet & bathtub but not to the extent that some well water does; we don't get red stained whites when we do our laundry...
The exception, of course, would be two years ago when we had a break in the line, and didn't know it. Our well has a 4' casing that goes down 10', then from there it's just a 4" pipe down the rest of the way, with a submersible pump. The line broke down in that 4" pipe, so every time the pump ran some water was going back down the well, and eventually it filled up & flooded the 4' casing, which has a dirt floor in it...I was having a lot of stomach problems that year & was starting to think there was something dreadfully wrong with me me. One night I drank out of the hose while watering horses and thought gee, that's sure good water, better than the town supply. Then the next night I drank from the hose again & thought hmmm, that tastes a bit dirty, must be just from the rubber hose. The next night I happened to be by the well casing, and heard some odd water running sounds that shouldn't have been there, so I looked, and it had several inches of water in it. I'd been drinking that disgusting, filthy water and up to the previous night thought it tasted great.
At least I then knew why my stomach had been playing me up for weeks, and there was nothing really wrong with me....we still cook with our water, but ever since then I've been buying Ultra Pure reverse osmosis water in town. Once in awhile when it's really hot & I'm really thirsty I do drink from the hose, but I can't bring myself to use our water for drinking on a regular basis. Besides, I kind of like having my tea without the "pond scum" our hard water always put on tea!!