Match the System to the Problem
The most common mistake well owners make with water treatment is buying a system before understanding what’s actually in their water. Always test first, then treat. Different contaminants require fundamentally different treatment approaches, and no single filter handles everything.
| Problem | Symptom | Treatment Solution |
|---|---|---|
| Bacteria | Positive test result; gastrointestinal illness | UV disinfection (after water quality clears); shock chlorination for existing contamination |
| Iron (ferrous/dissolved) | Orange-red staining, metallic taste | Oxidizing filter (greensand, Birm, MnO2) or water softener (for low levels) |
| Iron (ferric/particulate) | Orange water, turbidity | Sediment filter + oxidizing filter |
| Manganese | Black/brown staining, black specks at tap | Oxidizing filter; greensand or MnO2 media |
| Hardness | Scale buildup, soap scum, appliance damage | Ion-exchange water softener |
| Hydrogen sulfide | Rotten egg odor | Oxidizing filter; continuous chlorination; aeration |
| Low pH (acid water) | Blue-green staining, copper taste, pin-hole leaks | Calcite acid neutralizer; soda ash injection |
| Sediment/turbidity | Cloudy water, grit in fixtures | Sediment cartridge filter (5–10 micron); sand filter for high loads |
| Nitrates | No taste/odor; dangerous for infants | Point-of-use reverse osmosis; whole-house RO (expensive); ion exchange |
| Arsenic | No taste/odor; long-term health risk | Point-of-use reverse osmosis; adsorptive media filter (NSF-58 certified) |
| PFAS | No taste/odor; long-term health risk | Point-of-use reverse osmosis; granular activated carbon (NSF-58) |
Common Whole-House System Configurations
For Iron and Manganese
Oxidizing filters use a bed of media (greensand, Birm, or manganese dioxide) to convert dissolved iron and manganese into particles that are then filtered out. These systems backwash automatically to clean the media bed. For iron above 5 mg/L, a pre-treatment oxidation step (air injection, potassium permanganate, or chlorine injection) may be needed upstream of the media filter.
For Hardness
Ion-exchange water softeners replace calcium and magnesium ions (hardness) with sodium ions. They regenerate automatically using salt (sodium chloride or potassium chloride). A water softener alone does not treat bacteria, nitrates, arsenic, or most chemical contaminants. Softeners are typically installed after any sediment filtration and iron treatment.
For Low pH (Acid Water)
A calcite acid neutralizer raises water pH by dissolving calcite (calcium carbonate) as water flows through the media bed. It increases pH passively without chemicals and also adds beneficial hardness to the water. For very low pH (below 6.0), a blend of calcite and corosex (magnesium oxide) provides faster pH correction.
For Sediment
A sediment cartridge filter (typically 5–10 micron) is the first stage of any well treatment system. It protects downstream equipment (softeners, UV systems, RO membranes) from particles. Replace the cartridge every 3–6 months or when pressure drop across the filter exceeds 10 psi.
System Sizing Considerations
Whole-house systems are sized by flow rate (gallons per minute) to ensure adequate flow during peak demand. Key parameters:
- Determine your peak demand: typically the shower GPM × number of simultaneous showers + any other concurrent uses
- A typical 3–4 bedroom home requires 8–15 GPM capacity
- Size treatment equipment to match or slightly exceed the pump’s maximum output
- Undersized equipment creates pressure drop and premature failure