The steel industry recognises the importance of managing water sustainably given water’s essential value to society.

Even though the steel industry uses large quantities of water, very little of that water is actually consumed as most is reused or returned to source. For example, sea water is almost exclusively used in cooling operations and the loss during these processes may account for less than 1% of the total due to evaporation. Although the intake is considerable, the water is returned to the sea without any change in quality.

Water recycled back into rivers and other sources is often cleaner than when extracted.

The discharge of cooling water can significantly raise the temperature of the receiving water body and affect the aquatic ecosystems. Limitations on water discharge temperatures are sometimes applied to prevent deterioration from occurring.

In addition to being used in cooling operations, water is required throughout the steelmaking process for descaling, dust scrubbing and other processes.

The steel industry uses all types of water. Fresh water availability and quality is a major concern in large parts of the world and the management of water resources is considered to be the most important sustainability challenge after climate change.

Fresh water resources are at risk due to demands from a growing global population and increased industrial activity, in particular in developing countries.

The steel industry takes its responsibilities for water management seriously and is constantly evaluating how best to use water, finding improvements both in conservation and reuse.

In the same way as steel, water can be reused and recycled, thus improving efficiency of use and reducing demand as well as cost.

By increasing water recycling and cascading water use from higher to lower quality, steel producers have been able to reduce their water use and consumption considerably.

Key points from this report

Around 90% of water used in the steel industry is cleaned, cooled and returned to source. Water returned to rivers and other sources is often cleaner than when extracted.

Brownfield site limitations should be taken into consideration when assessing water management improvement possibilities.

Resource efficiency measures should consider actual consumption, i.e. difference between intake and discharge (of the same or better quality).

When considering the introduction of zero effluent discharge policies, legislators should take a holistic environmental approach to avoid shifting the burden from one environmental impact to another.

The steel industry supports the ISO 14046: 2014 standard for water footprints.

Local and/ or regional authorities are best placed to regulate steel industry water management.

Before implementing any water reuse management system, it is imperative to consider the impact on other resource categories, such as energy use.

Water usage objectives should always be linked to water availability and scarcity.

Whether a power plant is located on or off-site will impact a steel plant’s overall water use. This factor should be taken into consideration by legislators.

Water reuse

Energy consumption must be considered

The most effective way to reduce water intake is by reusing the water. This usually involves cleaning and cooling water flows between each use. Some of these treatments, such as cooling, require large amounts of energy and can lead to increased rates of water consumption due to greater evaporation.

The additional processes required are nearly always in conflict with objectives to reduce energy consumption or CO2 emissions. It is, therefore, necessary to assess the effectiveness of water reuse in an integrated manner, considering all environmental aspects.

It is imperative to consider the potential increase in energy use before implementing any water reuse management system.

As the reuse of water in a high-temperature industry can increase water consumption due to evaporation, it is crucial to have a holistic view of the overall impact on all environmental aspects.

Water intake and discharge

A worldsteel member survey published in 2011 showed that the average water intake for an integrated plant was 28.6 m3 per tonne of steel produced, with an average water discharge of 25.3 m3. For the electric arc furnace route, the average intake was 28.1 m3 per tonne of steel, with an average discharge of 26.5 m3. This demonstrates that overall water consumption per tonne of steel produced is low, ranging from 3.3 m3 to 1.6 m3. Most of the water is lost due to evaporation.

Water intake and discharge at 20 steel plants surveyed*, including sea water for once-through cooling
* Sample of results as reported in ‘Water management in the steel industry’ report, worldsteel, 2011

Water footprint calculation (ISO 14046: 2014) based on a life cycle assessment

In order to address all these issues and harmonise the methods, The International Organisation for Standardisation has developed a framework standard for calculating a water footprint (ISO 14046: 2014), published in July 2014. The standard is based on the ISO 14040-series for Life Cycle Assessment and defines what requirements are needed to complete a water footprint assessment, including local aspects related to both scarcity and quality.

It also covers the full life cycle, including upstream processes.
This standard is supported by the global steel industry.

The steel industry supports the ISO 14046:2014 standard for water footprints. It is currently the only methodology that contains all the factors necessary to assess a product, service or organisation’s water footprint.

A holistic approach to water management

Resource efficiency

Policies must look beyond water use