Iron dissolves naturally from the sediments the water passes through, especially in shallow, low-oxygen groundwater. It shows as orange stains, rust-colored laundry and, where iron bacteria grow, red-brown slime in toilet tanks. It is mainly a nuisance rather than a health risk, but it fouls pumps, screens and fixtures. Treatment depends on the type of iron a test finds.
Key points
- Orange stains and red slime are iron and iron bacteria.
- Shallow wells and irrigation wells carry more iron than deep ones.
- Iron fouls well screens and pumps over time.
- The type of iron decides the treatment.
Wellborne deals with iron in wells across Suffolk, Isle of Wight and Virginia Beach, most often on shallow wells and irrigation systems. It is usually more of a nuisance than a danger, but left alone it slowly clogs the well and the equipment.
Where it comes from
Iron is one of the most common elements in the sediments under the Coastal Plain. Groundwater low in oxygen dissolves it as it moves through those layers. Shallow water in the surface sands, where organic material uses up oxygen, tends to carry the most. USGS lists iron, with chloride and sulfur, among the reasons groundwater cannot be used in many parts of Virginia Beach.
Deep Suffolk wells usually carry less. In the Virginia Cooperative Extension clinic of 204 Suffolk households, most of them on deep wells, iron was above the 0.3 mg/L staining guideline in only about 3% of samples. Where iron trouble does appear in Suffolk, it is more often in shallow wells or from old galvanized pipe than from the deep aquifers.
Three kinds of iron
- Dissolved (ferrous) iron. Water comes out clear, then turns orange in a glass or leaves orange stains where it dries.
- Particulate (ferric) iron. Water comes out already cloudy, orange or rusty.
- Iron bacteria. Bacteria that feed on dissolved iron and build a red-brown, slimy growth in toilet tanks, pet bowls and anywhere water stands. They often bring a musty or swampy smell.
Each needs a different approach, which is why the test comes first.
What iron does to a well
Iron deposits and iron bacteria build up on well screens, pump intakes, check valves and inside pipes. Over years they choke the screen, reducing the well’s yield, and coat the pump, reducing its output. A well that slowly delivers less water and has a history of orange slime is a candidate for rehabilitation, which cleans the screen mechanically and chemically. Pressure switch sensing ports also clog with iron, causing erratic cycling.
What it does in the house and yard
Iron stains sinks, toilets, tubs and laundry orange or brown. In dishwashers and water heaters it settles as sludge. On irrigation wells, it stains siding, sidewalks, fences and cars wherever the sprinklers reach, and iron bacteria clog sprinkler heads and drip lines.
Treatment options
- Small amounts of dissolved iron: a water softener can remove it, at the cost of adding sodium. On deep Suffolk wells already high in sodium, that is a poor trade for drinking water.
- Moderate to high dissolved or particulate iron: oxidizing filters, which turn dissolved iron into particles and trap them, are the usual answer. Some also remove manganese and hydrogen sulfide.
- Iron bacteria: shock chlorination of the well knocks them back, but they usually return. Periodic well treatment, sometimes with continuous chlorination ahead of a filter, keeps them in check.
- Irrigation iron: an iron filter on the irrigation line, redirecting heads away from hard surfaces, or a different water source.
Treatment is sized to the household’s flow and the measured iron level. The treatment page covers sizing.
Old galvanized pipe
In older homes, rust-colored water can come from the plumbing rather than the well. Galvanized steel pipe corrodes from the inside over decades, especially with slightly acidic water. If the water from the well head is clear and only some taps run rusty, the house pipes are the likely source.
Sampling for iron
Iron results vary with how the sample is taken. Sample from a cold tap before any treatment, after running the water a few minutes. Ask the lab to report total iron, and manganese too, because they often occur together and affect the treatment choice. To talk through your results, call (757) 919-1972.