Recirculating aquaculture systems (RAS) represent an advanced approach to fish farming that prioritises water efficiency. Finnforel has developed water conservation practices within RAS technology, creating a closed-loop system that recirculates over 95% of water used in fish production. This approach significantly reduces water consumption compared to traditional aquaculture while minimising discharge risks. Through multi-stage filtration technology and precise environmental control, Finnforel produces rainbow trout using a production method designed to reduce water use and limit nutrient discharge into natural waterways.
What is a recirculating aquaculture system (RAS) and how does it conserve water?
A recirculating aquaculture system (RAS) is an advanced fish farming technology that continuously filters, treats and reuses water in a closed-loop environment. Unlike traditional aquaculture that requires constant water replacement, RAS conserves water by purifying and recirculating up to 99% of the water within the system, resulting in significantly reduced consumption and minimal discharge into natural waterways.
The water conservation process in RAS works through a sophisticated filtration system that removes waste products, adjusts temperature and oxygen levels, and maintains optimal water quality. This closed-loop approach means the same water can be used repeatedly for months, requiring only minimal top-up to replace evaporation losses. Discover how Finnforel’s fish farming practices are designed around responsible water management and reduced environmental discharge.
When compared with traditional open-net aquaculture or flow-through systems, the water savings are measurable. Conventional fish farms typically use between 50,000–100,000 litres of water per kilogram of fish produced. In contrast, RAS technology reduces this to just 500–1,000 litres – a reduction of approximately 99% in water consumption.
How does Finnforel implement water conservation in their RAS facilities?
Finnforel implements water conservation through RAS facilities that recirculate and purify over 95% of water used in fish production. Their Varkaus Gigafactory, with a 3-million-kilogram annual production capacity, features advanced filtration systems that continuously clean water, allowing it to be reused throughout the production cycle while maintaining optimal conditions for rainbow trout growth.
The company has designed their facilities with water efficiency as a core principle. At the Varkaus production plant, water is drawn from Lake Saimaa and undergoes continuous purification, ensuring both fish health and reduced discharge volume. The minimal discharge water that does leave the system is treated at the neighbouring Stora Enso water treatment plant, where fish-produced nitrogen is utilised rather than released as waste.
Finnforel’s approach extends to their Hollola breeding centre, which focuses on broodstock and fry production specifically optimised for RAS environments. This facility is Finland’s first selective breeding centre for rainbow trout, ensuring the entire production chain from eggs to consumer packaging maintains consistent water conservation standards.
What are the measurable environmental outcomes of RAS water conservation methods?
The measurable outcomes of RAS water conservation methods include significantly reduced water consumption, reduced nutrient discharge into natural waterways, lower waste volumes compared to flow-through systems, and a reduced overall water footprint per kilogram of fish produced. By operating a closed-loop system, Finnforel limits the discharge of nutrients that can affect aquatic ecosystems in conventional open systems.
A notable outcome is the reduction in water pollution risk. Traditional fish farms often release wastewater containing excess feed, fish waste, and sometimes medications directly into surrounding waters. Finnforel’s RAS technology captures these potential pollutants within the system, processing them through advanced filtration. The company reports that their phosphorus emissions are minimal, and they produce no nitrogen emissions in their production process.
Another measurable benefit is the reduction in transport-related emissions through localised production. By establishing RAS facilities near consumer markets — as demonstrated by Finnforel’s location in Finland — fish can be delivered to most cities by the following morning. This reduces the distance travelled from farm to consumer compared to imported alternatives, which in turn reduces the transport emissions associated with delivery.
How much water does Finnforel’s RAS technology save compared to conventional fish farming?
Finnforel’s RAS technology uses approximately 99% less water per kilogram of fish produced compared to conventional fish farming methods. While traditional aquaculture typically requires 50,000–100,000 litres of water per kilogram of fish produced, Finnforel’s closed-loop system reduces this to just 500–1,000 litres per kilogram — a significant reduction in water use per unit of production.
This water efficiency translates to substantial annual savings. With Finnforel’s Varkaus Gigafactory producing 3 million kilograms of rainbow trout annually, the facility uses considerably less water each year compared to equivalent production volumes using conventional flow-through methods. The water that is used remains in the system, constantly filtered and recirculated rather than discharged into natural waterways.
The water conservation approach also enables year-round production regardless of external weather conditions or seasonal variations. This consistency supports stable supply, quality, and pricing — benefits that extend beyond reduced water use to create operational and food security advantages as well.
What technological innovations make water conservation possible in Finnforel’s RAS?
The technological innovations making water conservation possible in Finnforel’s RAS include multi-stage filtration systems, real-time water quality monitoring, energy-efficient pumping technology, and integrated waste management. These systems work together to maintain optimal water conditions while minimising both consumption and discharge volume.
Finnforel’s filtration system involves mechanical removal of solid waste, biological processing of dissolved waste compounds, and fine filtration that ensures water purity. Advanced sensors continuously monitor parameters such as oxygen levels, temperature, pH, and nitrogen compounds, allowing for precise adjustments that maintain ideal growing conditions.
Energy efficiency is another critical component of Finnforel’s water conservation technology. The company has implemented solar power at their Varkaus facility, with a recently expanded solar plant capacity of over one Megawatt (MW), producing approximately 800 Megawatt hours (MWh) annually. At peak production, this solar plant generates more than a third of the daily energy needed for their aquaculture operations, helping to offset the energy requirements of water purification and circulation.
How does water conservation in RAS contribute to lower-impact food production?
Water conservation in RAS contributes to lower-impact food production by addressing several measurable resource challenges simultaneously: it reduces pressure on freshwater resources, limits nutrient discharge into aquatic environments, decreases dependence on wild fish stocks, and produces a consistent protein source with a significantly lower water footprint per kilogram than conventional aquaculture. These are operational characteristics of the RAS model, not general claims of superiority.
As global fish consumption continues to rise — according to FAO statistics, aquatic foods constitute 15% of the world’s animal protein intake, with per capita consumption having more than doubled over the past 60 years — production methods that measurably reduce water use and nutrient discharge become increasingly relevant. Finnforel’s water-efficient RAS technology is designed to meet this growing demand while using significantly less water per kilogram of fish produced than conventional methods.
The company’s production practices have earned certification from the Aquaculture Stewardship Council (ASC), a globally recognised third-party certification that verifies their fish farming meets defined environmental and social criteria. This certification gives consumers access to independently verified information about how the fish is produced. Contact Finnforel today to learn more about their fish farming methods and how their RAS technology is designed to reduce water use and nutrient discharge throughout the production process.
