How do you remove 20 ppm of iron from well water at pH 8?
| Treatmentair oxidises the iron in a tank before a filter catches it — no chemicals to refill | aeration plus filtration |
|---|---|
| Typical installed cost | $2,500–4,500 |
| Iron form at this pHcloudy straight from the tap | ferric (oxidised) |
| IronEPA secondary standard is 0.3 ppm | 20ppm |
| EPA threshold | 0.3ppm |
| Load added to a softenerabout 4 gpg of hardness capacity per 1 ppm of iron | 80gpg equivalent |
Notes
- pH decides the method, and almost nobody measures it. Below pH 7 iron is dissolved — the water looks clear at the tap and stains minutes later. At pH 8 it is already oxidised, so it arrives as particles and the water is cloudy from the moment it leaves the tap. This single number is why advice online contradicts itself: everyone is right for their own pH.
- At 20 ppm a softener alone will not cope, whatever the pH. It needs a filter that oxidises the iron and then catches it, ahead of any softener.
- Treat iron before the softener, never after. Whatever the method, iron removal goes first in the line. A softener downstream of clean water lasts; a softener taking raw iron is a filter that was not designed to be one.
- Get a real lab test, not a strip. You need iron, pH, manganese, hardness and — if there is a smell — hydrogen sulphide. Manganese behaves like iron but stains black instead of orange, and it needs a higher pH to oxidise. A test strip gives you one of those five numbers, badly.
- Iron bacteria are a different problem with the same symptom. If there is orange slime in the toilet cistern rather than a stain, no filter will fix it — that needs shock chlorination of the well itself first.
20 ppm of iron at pH 8
The iron here is ferric (oxidised), and the method that works is aeration plus filtration.
pH decides the method, and almost nobody measures it
Everyone tests iron. Very few test pH — and pH is what chooses the equipment.
| pH | Iron form | What it looks like |
|---|---|---|
| below 7 | ferrous, dissolved | clear at the tap, stains minutes later |
| 7 and above | ferric, oxidised | cloudy the moment it leaves the tap |
A softener can hold dissolved iron. It cannot hold particles — those foul the resin bed instead of binding to it.
This is why advice online contradicts itself. Everyone is right for their own pH.
Iron eats softener capacity
Every 1 ppm of iron costs roughly 4 gpg of hardness capacity. At 20 ppm that is about 80 gpg added to whatever the water test said.
Sizing a softener on hardness alone is why a correctly chosen unit still delivers stained water by day five.
Treat iron before the softener, never after
Whatever the method, iron removal goes first in the line.
A softener downstream of clean water lasts. A softener taking raw iron is a filter that was never designed to be one.
Get a lab test, not a strip
You need iron, pH, manganese, hardness, and — if there is a smell — hydrogen sulphide.
Manganese behaves like iron but stains black instead of orange, and it needs a higher pH to oxidise. A test strip gives you one of those five numbers, badly.
Orange slime is a different problem
If the toilet cistern has slime rather than a stain, that is iron bacteria. No filter fixes it — the well itself needs shock chlorination first.
Nearby sizes
Read more
- Sediment Filters — The Cheapest Stage and the One That Protects EverythingEverything downstream lasts longer because of a filter that costs almost nothing.
- Stains — Reading the Colour to Find the CauseThe colour of the stain is the diagnosis, and households treat the wrong thing because nobody said so.
- Iron, Manganese and Rotten-Egg Smell — Identifying Before TreatingOrange stains, black stains and a rotten-egg smell are three separate problems that get sold the same filter.
- Reverse Osmosis at the Kitchen Tap — What It Removes and What It WastesThere is no reason to purify the water that flushes the toilet.