Guides
Diagnostic guides: a symptom or a lab result in, a treatment class out, with the EPA or NSF limit cited by number.
Each guide starts from something you can see, smell or read off a test report, and ends at the class of equipment that fixes it. The regulatory limit is cited by number, and the sizing or part page that follows is linked from the guide.
Black stains from well water: how much manganese that is and what removes it
Black stains on a private well mean manganese above EPA's secondary standard of 0.05 mg/L. Why it resists iron treatment, and which class fits each mg/L range.
Blue-green stains and pinhole leaks: low pH well water and what neutralizes it
Blue-green stains on a well are copper dissolved by low-pH water. EPA's pH range is 6.5 to 8.5; an acid-neutralizing filter treats down to pH 5.3.
How to shock chlorinate a well: chlorine amount, contact time, and when it is the wrong fix
Shock chlorinate a well at 50 to 200 ppm with plain 6% or 8.25% bleach, hold it 2 to 6 hours or overnight, flush to 0 ppm, retest in 2 to 4 weeks.
Iron in well water: how much is behind the rust stains, and what treats it
Rust stains on a private well mean iron at or above the EPA secondary standard of 0.3 mg/L. Which form it is, and which treatment class fits each mg/L range.
Rotten egg smell in well water: hydrogen sulfide levels and what removes it
Hydrogen sulfide has no EPA limit; the nose finds it at 0.05 to 0.1 mg/L. Hot tap only means the heater anode, both taps means the well, and the mg/L picks the fix.
Tea-colored well water: tannins, how to tell them from iron, and what removes them
Tea-colored well water that stays colored after a glass sits overnight is tannins, not iron. EPA lists color at 15 units; the fix is anion resin, carbon or RO.
What to test well water for: the annual panel, the units, and what each result decides
A private well needs coliform, nitrate, TDS and pH every year at a certified lab (CDC, EPA). Nitrate limit 10 mg/L as N. Which symptom adds which test.
White Scale on Faucets and Kettles: How Hard Your Water Is and What Fixes It
White crust on faucets and kettles is hardness scale. Hardness in gpg and mg/L (1 gpg = 17.1 mg/L), the USGS bands, and why 7.0 gpg is the line for a softener.