Well here's my take.
We had what looked like nice clear water from our well into our 3000 L tank.
I noticed that the bathroom shower tiles were turning a rusty color, so decided to investigate the water.
Short story is you need to get your water professionally tested at the Amphur.
(My theory): The iron is in the water, but it doesn't oxidise until the water mixes with the air so then the iron precipitates out and gives that rusty look.
Once you get your water analysed you will know what filtets to install to filter out all the iron etc.
So my aquifer water goes into a 3000L settlement tank, then to 2 big backwashable filtets in series. One filter has active carbon and the other crushed plate glass. From there it goes to a Big Blue sediment filter ....from there (for the drinking water) to a 6 stage reverse osmosis filter.
All this came about from rusty looking tiles and water analysis.
6 L of water and about B6000 is what Khon Kean university charge for detailed water analysis 5 or 6 years ago.