Iron in Tap Water UK: Brown Water, Taste & What to Do

What Causes Iron in Tap Water?

Iron can enter your tap water from several sources:

  • Old cast iron mains: Many UK water mains are over 50 years old and made of cast iron. As they corrode internally, iron particles enter the water.
  • Mains disturbance: Work on water mains, burst pipes, or changes in flow direction can dislodge iron sediment, causing temporary discolouration.
  • Internal plumbing: Old iron or galvanised steel pipes within your property can corrode and release iron.
  • Natural sources: Some groundwater supplies naturally contain dissolved iron from geological formations.

UK Legal Limits

The DWI limit is 200 ppb (0.2 mg/l). This is an aesthetic standard — it exists because iron causes unpleasant taste and discolouration, not because it's a health risk at these levels. Most UK tap water contains 10-50 ppb of iron.

Health Effects

Iron is an essential mineral. Adults need 8.7-14.8 mg per day from food and drink. The amount in tap water (even at the legal limit) contributes a tiny fraction of this. Iron in water is not a health concern for most people. However, people with haemochromatosis (iron overload condition) should be aware of all dietary iron sources.

Brown or Discoloured Water

If your water runs brown, orange, or rusty:

  • Run the cold tap for 2-5 minutes — it often clears
  • Do not use it for laundry until it clears — it will stain white clothes
  • If it persists beyond a few hours, contact your water company
  • If only hot water is affected, the issue may be your hot water tank or boiler

Check Your Water's Iron Level

Enter your postcode on WaterGrade to see the iron measurement for your water supply zone.

Frequently Asked Questions

Why is my tap water brown?

Brown or orange tap water is usually caused by iron. This can come from old iron water mains, corroded pipes in your property, or natural iron in the water source. It often happens after work on the water mains disturbs sediment, or when water flow direction changes. It is usually temporary and clears within a few hours.

Is iron in tap water harmful?

Iron in tap water at the levels found in UK supplies is not harmful to health. The UK legal limit is 200 micrograms per litre (200 ppb), set primarily for aesthetic reasons — iron causes discolouration, metallic taste, and can stain laundry and sanitaryware. Iron is an essential mineral that your body needs.

What is the legal limit for iron in drinking water?

The UK limit for iron in drinking water is 200 micrograms per litre (200 ppb or 0.2 mg/l). This is an aesthetic standard, not a health-based one. Even water above this level is safe to drink, but it may be discoloured, have a metallic taste, or stain laundry.

What should I do if my water is brown?

Run the cold tap for a few minutes to see if it clears. If it persists for more than a few hours, contact your water company. Do not use discoloured water for laundry as it may stain clothes. If it happens regularly, your internal plumbing may need attention.

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