If you are on a well in East Gwillimbury, King, Whitchurch-Stouffville or Georgina, there is a good chance you know the orange ring in the toilet and the smell at the tap. Both are common, both are fixable, and neither needs chemicals.
Where iron comes from
Groundwater moving through the Oak Ridges Moraine and the sediments beneath York Region dissolves iron and manganese from the rock. In the aquifer, with no oxygen, they stay dissolved and invisible. The moment the water meets air, at the tap, in the toilet tank, on the laundry, they oxidize into the orange and black particles that stain. That is why a glass of well water can look clear and still ruin a load of whites.
Where the smell comes from
Hydrogen sulphide gas, produced when certain bacteria in the aquifer act on sulphur compounds. It is the rotten-egg smell, and it is strongest at the hot tap because heat drives the gas out of the water. If the smell is only at the hot tap and not the cold, the culprit is often the magnesium anode inside the water heater reacting with sulphate, and a different anode fixes it. If both hot and cold smell, it is the well.
Why a softener is the wrong tool
Softeners can handle a trace of iron, and salespeople sometimes sell them for it. Above a low threshold, iron coats the resin and the softener fails within a year or two. Iron has to come out before the softener, not in it.
The fix: oxidize, then filter
An oxidizing filter does on purpose what your toilet tank does by accident. A pocket of air in the top of the tank, or a catalytic media bed, oxidizes the dissolved iron, manganese and hydrogen sulphide into solids as the water passes. The media traps the solids, and a backwash every day or two flushes them to drain. No chlorine, no salt, no chemical feed. The Honest Water iron and sulphur filter, built in Barrie, Ontario, works on this air injection principle.
Sizing depends on the levels of each, the pH, and your peak flow. Low pH, which some wells in the area have, stops oxidation working, so a pH correction stage goes in first. Iron bacteria, which leave a slimy film in the toilet tank, need the well shocked before a filter will stay clean.
Signs your well has iron or sulphur
- An orange or brown ring in the toilet bowl and tank.
- Rust-coloured stains on laundry, sinks, tubs and the dishwasher.
- Black specks or black staining, which usually means manganese.
- A rotten-egg smell, strongest when you first turn on the tap or at the hot tap.
- Metallic-tasting coffee and tea, or discoloured ice.
- A softener that keeps failing or a sediment filter that turns orange within weeks.
Where it goes in the sequence
After the pressure tank and a sediment filter, before the softener and any UV. Put it in the right place and it protects everything downstream. Our well water treatment page walks through the full sequence.
Test first
Iron, manganese, hydrogen sulphide and pH, from one visit. Our in-depth well water testing gives you the numbers that decide the media and the size, and tells you whether the smell is the well or the water heater before you spend anything. Iron and sulphur are not the only things to check on a private well: our guide on how to test your well water in Ontario covers the free bacteria test as well.
Common questions
Is iron in well water harmful?
Iron itself is treated as an aesthetic problem, not a health one. Health Canada sets an aesthetic objective for iron of 0.1 mg/L or less, based on staining and taste. Manganese is different: it has a health-based maximum acceptable concentration of 0.12 mg/L and an aesthetic objective of 0.02 mg/L. Both figures are in the Guidelines for Canadian Drinking Water Quality summary table. Because iron and manganese usually travel together, a test for one should always include the other.
Why does only my hot water smell like rotten eggs?
Usually the water heater, not the well. A magnesium anode rod inside the tank can react with sulphate in the water and make hydrogen sulphide. Swapping to a different type of anode often solves it. If the cold water smells too, the gas is coming from the well and needs treatment.
Is the rotten-egg smell dangerous?
At the levels that make well water smell, hydrogen sulphide is mainly a nuisance. Health Canada sets an aesthetic objective for sulphide of 0.05 mg/L or less, which is about taste and odour. It is still worth fixing: it tarnishes silver, corrodes plumbing and makes the water unpleasant to use.
Can a water softener remove iron?
Only a small amount. More than a trace coats the resin and cuts the softener's life short. The right order is iron filter first, softener second.
Will an iron filter also remove manganese and sulphur?
An oxidizing filter sized for your water handles iron, manganese and hydrogen sulphide in the same tank. The test results decide the media and tank size so it keeps up with all three.
What are iron bacteria and how do I get rid of them?
Harmless bacteria that feed on iron and leave a red, slimy film in the toilet tank and a swampy smell. They are dealt with by shock chlorinating the well and plumbing, then treating the water so they do not come back. A filter installed without that step fouls quickly.