Understanding High Levels of Iron in Closed Water Systems

Iron is a common element that, although essential in small amounts, can cause significant problems when present in high concentrations within closed water systems.

We’ve encountered numerous cases where closed systems struggle with high iron levels, prompting the question, “Why is this happening?” Let’s explore how iron can infiltrate your system, the damage it can cause, and, most importantly, the best treatments to address this issue effectively.

What is Iron and How Does it Get into Closed Water Systems?

Iron in closed water systems can exist in two primary forms: ferrous iron (dissolved iron) and ferric iron (particulate iron). Ferrous iron is soluble and remains in solution until it oxidizes to ferric iron, which precipitates as rust particles.

Iron can enter closed systems through several pathways:

  • Corroded Components: Iron can leach into the water from corroded pipes, heat exchangers, and other metal components within the system.
  • Makeup Water: Freshwater added to the system to replace losses can introduce iron, especially if the source water has high iron levels.
  • Residual Construction Materials: Iron particles from construction materials or debris left in the system can dissolve into the water over time.

How Iron Affects Water Quality and System Performance

High levels of iron in closed water systems can lead to various issues:

  • Corrosion: Iron can accelerate the corrosion of metal components, leading to leaks, reduced efficiency, and potential system failures.
  • Clogging and Fouling: Iron precipitates can form deposits on heat exchangers, pipes, and valves, reducing heat transfer efficiency and restricting flow.
  • Microbial Growth: Iron can support the growth of iron-oxidizing bacteria, which form biofilms and exacerbate corrosion and clogging problems.
  • Reduced Efficiency: The presence of iron deposits can decrease the efficiency of heating and cooling processes, leading to higher energy consumption and operational costs.

Systems Most Commonly Affected by High Iron Levels

Certain closed water systems are particularly susceptible to high levels of iron for various reasons:

Heating Systems: Boiler systems and hot water loops can experience significant iron-related issues due to high temperatures and the presence of oxygen, which promotes iron oxidation and deposition.

Chilled Water Systems: Chilled water loops, including HVAC systems, can also be affected by iron, especially in systems that frequently add makeup water or have poorly maintained corrosion control programs.

Industrial Cooling Systems: Closed-loop cooling systems in industrial settings are at risk of iron contamination, which can impact process efficiency and equipment lifespan.

Best Methods and Practices to Remove Iron from Closed Water Systems

Effectively managing iron levels in closed water systems requires a combination of preventive measures and treatment solutions:

Image: The results of our Hierro Filter on a Chilled System

Hierro Filters: Our Hierro Filters are highly effective at eliminating iron from water. These filters capture iron particles, preventing them from causing clogging and buildup within the system. Regular cleaning and replacement of these filters are essential to ensure optimal performance and longevity.

Chemical Treatment: Use corrosion inhibitors and oxygen scavengers to prevent the oxidation of ferrous iron and protect metal surfaces from corrosion. These chemicals help maintain water quality and reduce iron deposition.

Regular System Flushing: Periodically flush the system to remove accumulated iron deposits and other contaminants. This helps maintain efficient heat transfer and prevents clogging.

Deaeration: Use deaerators to remove dissolved oxygen from the water, reducing the potential for iron oxidation and subsequent deposition.

Image: Water filter clogged with iron. Our filters are highly effective, but you must remember they also need to be cleaned!

Water Softening: Treat makeup water with a water softener to remove iron before it enters the closed system. This helps minimize the introduction of new iron into the system.

Monitoring and Testing: Regularly test the water for iron levels and other key parameters. Monitoring allows for early detection of iron-related issues and timely adjustments to treatment programs.

Maintenance and Inspection: Conduct routine maintenance and inspections of the system components to identify and address corrosion and iron buildup before they cause significant problems.


High levels of iron in closed water systems can lead to a range of issues, from corrosion and clogging to reduced efficiency and increased operational costs. Understanding how iron enters these systems and the impact it can have been crucial for effective management. By implementing the right combination of treatment methods and preventive measures, you can ensure your heating and chilled water systems remain efficient, reliable, and free from iron-related problems. If you suspect high iron levels in your closed water system, you can get in touch today and we will help develop a tailored treatment solution for your needs.