Challenging raw water quality (whether ground water or not!) frequently has a geological origin. Understanding the geological origin can help those responsible for the operation of a ground-water system (or even operators of a public water supply reservoir) to make decisions to either avoid or mitigate undesirable water quality. For well water supplies, sometimes a very simple strategy of changing well depth or pumping rates can avoid a problem and reduce or eliminate treatment requirements. Installing and operating a properly designed water treatment system cannot always be avoided (and probably shouldn’t be).