The Transformers Foundation has released a comprehensive industry benchmark for water consumption during indigo dyeing, establishing reference standards that could transform how denim mills measure and report their environmental impact. The study involved seven global mills and machinery manufacturers to create verifiable metrics for both rope and slasher dyeing processes.
- Average water consumption ranges from 15–20 litres per kilogram for rope dyeing and 10–15 litres per kilogram for slasher dyeing.
- Best practices can reduce consumption to 3.85 litres per kilogram for rope dyeing and 3.40 litres per kilogram for slasher dyeing.
- The study aims to prevent greenwashing by providing universal benchmarks against which sustainability claims can be measured.
KEY TAKEAWAY: This pioneering research addresses a critical gap in denim sustainability reporting by establishing the first scientifically validated benchmarks for indigo dyeing water consumption. The standards provide brands and suppliers with verifiable metrics to evaluate environmental claims and could fundamentally change how the industry approaches water efficiency improvements.
- Indigo efficiency rates should achieve 93-95% for rope dyeing and 85-94% for slasher dyeing processes.
- The study focused on dark indigo shades requiring approximately 4% indigo ratio on 100% cotton warp yarns.
- Pre-reduced liquid indigo was specified as the sustainable standard, reducing chemical usage by up to 70%.
THE BACKDROP: The Transformers Foundation formed the Indigo Council in February 2024 following discussions with mills that began in August 2023. The initiative responded to widely varying and often incorrect water usage claims in marketing campaigns, sustainability reports, and pitch decks that opened the door to greenwashing across the denim industry.
THE STUDY: The research involved mills from Italy, Türkiye, Pakistan and China, covering both rope dyeing and slasher dyeing methods. Participating companies included Soorty, Naveena Denim, Candiani Denim, Crescent Bahuman, Orta Anadolu, Diamond Denim and Advance Denim. Technical oversight came from Morrison Textile Machinery Co and Karl Mayer, with independent validation from the Bluesign certification system.
CONTEXT FRAME: The global fashion industry consumed 79 billion cubic metres of water in 2015, with denim frequently criticised for its water and chemical usage. Experts estimate 3 billion–5 billion denim garments are manufactured annually, requiring approximately 66,000 tonnes of indigo powder combined with sometimes hazardous chemicals to create liquid dye solutions.
- Many denim suppliers have implemented machinery and processes to reduce water and chemical requirements.
- Marketing claims about water savings rarely acknowledge the complexity and diversity of indigo dyeing processes.
- Prior to this study, no comprehensive method existed for gathering and comparing data across different dyeing recipes and procedures.
YES, BUT: The study excluded several important factors that could affect real-world water consumption in commercial operations. Wastewater treatment, chemical usage, and water recycling were not included in the scope, despite being standard practices at most participating mills.
- The research focused only on post-dyeing washing processes, not total water consumption including pre-dyeing and actual dyeing stages.
- Manual adjustments by operators can lead to variability in water usage data beyond the controlled study conditions.
- Some mills rely on simpler monitoring systems whilst others use advanced automated control technologies.
WIDER LENS: The European Parliament's Green Claims Directive, passed in 2024, bans misleading environmental claims without concrete evidence. Terms like "environment-friendly" and "climate neutral" can no longer be used in advertising without scientific backing, with member states having two years to introduce new rules.
- The United Kingdom's Green Claims Code prevents financial firms from making misleading environmental claims.
- Several fashion brands in the United States have faced lawsuits for making misleading environmental product claims.
- Water scarcity and rising costs are driving manufacturers to explore more aggressive water reduction methods.
VOICES ON RECORD: The study revealed varying perspectives on rope versus slasher dyeing methods among participating mills. Suat Özdemir from Crescent Bahuman stated that the choice between rope and slasher dyeing "is a question that never gets old in the denim world and there is no single correct answer."
- Stefano Agazzi from Karl Mayer noted that water usage depends on solidity achieved in indigo dye boxes and various processing parameters.
WORTH NOTING: The study established specific technical parameters to ensure comparable results across different mills and machinery types. All participating mills confirmed they do not use fixing agents or resins to artificially reduce water usage, maintaining the integrity of the benchmark data.
- Mills were permitted to use their standard yarn counts as long as they remained close to the Ne 9 specification.
- Oxidation lengths varied between 40–50 metres for rope dyeing and 20–37 metres for slasher dyeing across different mill operations.
- The research used dyeing of 3,000 metres of warp yarn as a standardised reference point for consistent measurement.
WHAT THEY SAID:
One of the most encouraging findings in this report is the willingness of mills to work together and share data transparently, a testament to Transformers culture of collaboration. It’s a powerful reflection of the strength and integrity of our supply chain. Prior to this report, claims like ‘80% less water’ have frequently gone unchallenged. Without transparency and specificity, such figures become marketing jargon: just enough to sound responsible, never enough to be meaningful. Real sustainability requires real data, and this report provides exactly that.
— Andrew Olah
Founder
Transformers Foundation
Naveena NDL Denim has been focused on optimizing and innovating in denim production from the very beginning. That’s why we’re proud to collaborate on this industry-first benchmark for water consumption. Setting industrial standards prevents sustainability from becoming a buzzword, and keeps brands and suppliers accountable.
— Rashid Iqbal
Executive Director
Naveena NDL
This report marks a historic first in the denim industry, bringing together mills from across the globe to share verified, third-party data on actual water use. Our goal was not to rank mills, but to equip brands, designers, and retailers with meaningful benchmarks, enabling them to assess how seriously a mill is addressing water reduction. Most importantly, this report proves that open, honest collaboration is possible even among competitors when it comes to critical sustainability issues
— Paolo Leidi
Technical Director
Transformers Foundation
