Symptom matching · test first
What is the water doing?
Match the stain, the smell, or the lab sheet to a treatment class. Then compare systems. Well Diagnosis is a problems → tests → treatment-class diagnostic site for private-well homeowners.
Six common complaints
Catalog
Stain
Orange stains
Rust on fixtures, laundry, or a toilet tank. Iron, manganese, or iron bacteria — not the same treatment class.
Smell
Rotten-egg odor
Hydrogen sulfide from the aquifer, sulfur bacteria, or a water-heater anode. Hot-only vs. every tap changes the fix.
Scale
White scale
Hardness leaves crust on kettles and fixtures. A softener is not an iron filter. Test both before you buy either.
Slime
Slimy tank
Orange or brown jelly in the toilet tank is usually iron bacteria, not just dissolved iron. Filters clog if you skip this.
Corrosion
Blue-green corrosion
Blue-green on sinks or pinhole leaks often tracks with low pH and copper. Read the lab sheet before a neutralizer.
Flow
No pressure
Short cycling, sputtering, or a tank that feels waterlogged is a pressure-tank problem. Fix the tank before you size treatment.
Start with a test
EPA and CDC tell private-well owners to test every year for total coliform bacteria, nitrate, total dissolved solids, and pH. A stain or a smell is a clue, not a specification. Use a certified lab for decisions that cost a tank and a weekend of plumbing.
Treatment order
After the pressure tank, order matters: sediment, then oxidation or neutralization as the water chemistry requires, then softening, then carbon if you still need it, then UV last. Bacteria or nitrate is a health-department conversation, not a shopping cart.
00
Pressure tank
Already in the house. Fix this before you size treatment.
01
Sediment
Protects every tank downstream.
02
Oxidation or neutralization
Iron, sulfur, or low pH — only if the lab sheet says so.
03
Softening
Hardness. Not a substitute for an iron filter.
04
Carbon
If you still need taste, odor, or chlorine residual.
05
UV last
After the water is clear. Bacteria still belongs with the health department.
Treatment order after the pressure tank
The usual sequence. Stacking units in the wrong order is how systems fail.
Iron filter vs. water softener
Two different jobs. A softener is not a substitute for an oxidizer.
Whole-house iron and sulfur filters
Air, chlorine, catalytic media, and carbon — matched to the lab numbers.
UV vs. shock chlorination
A one-time well disinfection is not the same as continuous UV at the house.
State labs and contaminant pages
Inventories and contaminant × state guides already on this site. Start at Certified labs by state. The bacteria reading order is Coliform Bacteria in Well Water.