Red or Orange Water

Red, orange or reddish-brown water is often caused by iron, natural organic matter or a combination of both. Iron occurs naturally in many groundwater sources and may be completely invisible when dissolved. When exposed to oxygen, iron oxidises and forms particles that produce yellow, orange, red or brown colours. Natural organic matter from soils, forests and wetlands may also contribute yellow, brown or reddish-brown tones.

In many waters, iron and natural organic matter form complexes, meaning that iron ions become bound to organic molecules. These complexes may create intense reddish-brown colours and can make iron more difficult to remove using conventional aeration and filtration. The colour may originate from the water source itself, but also from plumbing systems, water heaters or other installations affected by corrosion. Significant colour changes should therefore be viewed as an indication that water chemistry or infrastructure conditions have changed.

The colour may originate from the water source itself, but also from plumbing systems, water heaters or other installations where corrosion occurs. Just as green colours are often associated with copper, red, orange and brown shades are frequently linked to iron and its oxidation products. Significant colour changes should therefore be seen as an important indication that water chemistry or infrastructure conditions have changed.

Did You Know?

Red water is not always caused by rust. Many forested and wetland areas contain large amounts of natural organic matter that gives water a brown or reddish-brown colour. When iron is also present, stable iron-organic complexes may form, creating even stronger colours. These complexes are often more difficult to treat than ordinary iron-rich water. As a result, two waters with the same iron concentration may appear completely different depending on their organic content.

Common Causes

• Elevated Iron Levels in Groundwater
• Natural Organic Matter from Soil and Wetlands
• Iron-Organic Complexes
• Oxidation of Dissolved Iron
• Corrosion of Steel or Cast-Iron Pipes
• Particles Released from Aging Pipe Networks

Common Symptoms

• Red, Orange or Rust-Coloured Water
• Staining of Sinks and Toilets
• Rust-Coloured Deposits
• Metallic Taste
• Particles Following Stagnation or Pipe Work

Common Treatment Methods

• Water Analysis
• Aeration and Oxidation
• Ozone Treatment
• Iron and Manganese Filters
• Pipe Flushing
• Inspection of Corrosion and Infrastructure

Example Treatment Trains