UK legal limit: 200 µg/L. Find out what iron is, its health effects, and how to check and reduce it in your tap water.
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Iron is one of the most common causes of tap water quality complaints in the UK. When iron enters tap water at detectable concentrations, it produces a characteristic orange-brown or rust-coloured discolouration and a metallic taste. Iron in tap water comes almost entirely from the distribution network rather than from source water or treatment — specifically from the corrosion of ageing unlined iron water mains that make up a significant proportion of the UK's water infrastructure.
The UK legal limit for iron in tap water is 200 µg/L (0.2 mg/L). At this concentration, water will typically have a noticeable reddish-brown tint and a metallic taste. Most UK tap water contains far less than this — typically 5–30 µg/L. Iron becomes a problem primarily in two scenarios: when water mains are disturbed (by road works, high demand, or flow changes), which can dislodge iron deposits from pipe walls; and in homes with iron or steel internal plumbing, particularly in older properties.
Iron is an essential dietary mineral — deficiency (anaemia) is far more common than toxicity. At the concentrations found in UK tap water, even in zones with occasional discolouration events, iron is not harmful to health. The WHO does not set a health-based guideline for iron because concentrations high enough to cause any health concern would be extremely obvious from taste and appearance long before they posed any risk.
The concern with iron in tap water is almost entirely aesthetic: staining of fixtures, laundry, and sinks; metallic taste; and discolouration of hot drinks. Orange-brown staining in baths, sinks, and around tap aerators is a classic sign of iron in the water supply.
If you experience a one-off discolouration event — which can follow nearby water main work or a period of low flow — run the cold tap until the water clears. Report persistent or recurring discolouration to your water company, who has a legal obligation to investigate. For properties with chronic iron issues (often older homes with iron internal pipework), a whole-house iron filter or point-of-use filter can be effective. Replacing iron or steel internal pipework with copper or plastic will address the source.
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Orange or brown tap water is typically caused by iron — either from disturbance of deposits in iron water mains or from corrosion of iron pipes in your home. Run the tap until clear and report to your water company if it persists.
At UK tap water concentrations, iron is not harmful to health. Iron is an essential dietary mineral. The concern is aesthetic — discolouration and metallic taste — not a health risk.
The UK legal limit for iron in drinking water is 200 µg/L (0.2 mg/L). At this concentration, water will be visibly discoloured. Most UK water contains far less than this.
Yes. Whole-house iron filters, under-sink filters, and reverse osmosis systems remove dissolved iron. Standard jug filters have limited effectiveness. For severe iron issues, a plumber-installed whole-house filter is the most effective solution.
Persistent iron issues are usually caused by ageing iron water mains or iron internal plumbing in older properties. Report chronic discolouration to your water company. Replacing old iron internal pipes with copper or plastic will address household-level iron.
No — avoid drinking visibly discoloured water and run the tap until clear. If the problem persists or returns, contact your water company. One-off discolouration events are common after nearby main work or flow changes.