The colors you see are actually iron stains. Iron is very common in well water and can be found in three different forms: Ferrous Iron (dissolved-not visible; this is the most common type of iron. Water appears clear when drawn but when mixed with oxygen turns yellow), Ferric Iron (suspended-visible; this type is mixed with oxygen which forms an actual particle that can be seen), and Iron Bacteria (this is harmless bacteria that feeds on iron forming a slimy growth in pressure tanks, softeners, plumbing, and toilet tanks. This type also clogs filters and is difficult to remove)