Well water treatment
A private well has nobody behind it publishing a water quality report, so treatment starts with a lab test rather than a product. A state-certified test costs roughly $50 to $200 and tells you which of six or seven common problems you actually have. Most wells need two or three stages, in a fixed order: grit, then iron and manganese, then taste and chemistry, then bacteria.
The EPA recommends testing a private well every year for coliform bacteria, nitrate, total dissolved solids and pH. Add iron, manganese, hardness and hydrogen sulphide to the panel if you are about to buy treatment, because those four decide which system is the right one.
In this cluster
- Best well water filtration systems: scored and ranked, plus the ultraviolet certification class that decides whether a lamp is rated for well water at all
- Best whole house water filters: the same platform for municipal water
- Best under-sink reverse osmosis systems: the answer for nitrate and arsenic, which whole-house carbon does not touch
- How water filters work: why UV is disinfection rather than filtration, and what that changes
Reading your test result
A well test comes back as a list of numbers with limits beside them, and the useful question is not whether a number is high but what treats it and what that costs. This is that table.
| What | How you notice it | Where it starts to matter | What treats it | Rough cost |
|---|---|---|---|---|
| Iron | Orange or brown staining on fixtures, laundry and toilets; metallic taste | Above 0.3 mg/L is where staining starts | Catalytic media in a whole-house cartridge system, or air injection above about 3 mg/L | $300–550 as a cartridge stage |
| Manganese | Black specks and black staining, often alongside iron | Above 0.05 mg/L | The same catalytic media stage as iron, which is why they are sold together | Included with iron treatment |
| Hardness | Scale on kettles and shower screens, soap that will not lather | Above 7 grains per gallon, or 120 mg/L as calcium carbonate | Ion-exchange softener with a salt tank, or polyphosphate to slow scale without removing it | $600–1,500 for a softener |
| Hydrogen sulphide | Rotten egg smell, often stronger from the hot tap | Detectable by smell well below any health limit | KDF media or catalytic carbon; heavy loads need aeration | Included in a KDF whole-house stage |
| Coliform bacteria | None. It is invisible, tasteless and only a lab finds it | Any detection at all is a fail | Ultraviolet disinfection, fitted after filtration; shock chlorination first to clear the well | $300–500 plus a lamp yearly |
| Nitrate | None. Common near agriculture and septic systems | EPA limit 10 mg/L, and it matters most for infants | Reverse osmosis at the kitchen tap, or anion exchange for the whole house | $200–600 for under-sink RO |
| Arsenic | None. Geological, and regional rather than random | EPA limit 0.010 mg/L | Reverse osmosis, or iron-oxide adsorption media for the whole house | $200–600 for under-sink RO |
Three of those seven have no taste, no smell and no colour: coliform, nitrate and arsenic. They are the reason a test is worth more than any product on this site, because nothing about the water tells you they are there.
The three things that catch people out
Filtration is not disinfection. Sediment, carbon and iron media are filters, and no arrangement of them removes bacteria. A well that tests positive for coliform needs ultraviolet light, chlorination or a membrane, fitted after the filtration rather than instead of it.
A whole-house filter does not reduce dissolved contaminants. Nitrate and arsenic pass straight through carbon. Both are treated at the kitchen tap with reverse osmosis, which is cheaper than treating every outlet in the house to drinking-water standard, and it is the right trade because you drink and cook with a small fraction of what you use.
Iron above roughly 3 mg/L outgrows a cartridge. Catalytic media in a 20-inch housing handles ordinary well iron well. A heavy load blinds it quickly, and the answer there is air injection or an oxidising system, which is a larger and more expensive class of machine.
Where to start
Test, then buy in sequence, cheapest and most protective first. Nearly every well benefits from a flushable spin-down screen, because it is the cheapest stage there is and decides how often you touch anything else. What goes behind it is whatever your result actually says, and the ranked systems cover each case.