Municipal water
Start with your utility's Consumer Confidence Report (CCR). Use the report to identify disinfectant type and any reported contaminants, then decide what problem you are actually trying to solve: hardness, taste/odor, sediment or a certified reduction claim.
Private well
EPA recommends testing private wells and using certified laboratories. A well-water system should be based on measured chemistry and microbiology, not just taste, color or smell.
Important: A clear-looking well can still contain contaminants that cannot be seen, smelled or tasted. This planner does not test water.
What both sources have in common
Whole-house treatment still needs adequate service flow, pressure and maintenance access. The best system is not simply the one with the most stages.
Next step
Run your numbers through the Water System Planner, then verify any product against its actual service-flow, pressure-drop, capacity and certification data.