Episode 46: Does it really take 20,000 litres of water to make the cotton for a t-shirt and pair of jeans?




Cotton, myths, water use, misinformation, fashion, sustainability



Welcome to the Fashion Unearthed podcast. If you need help navigating the fashion industry sustainably, you have come to the right place. I'm your host Belinda Humphrey and my hope is to simplify the fashion industry so that businesses can make the best decisions for people, planet and product.


Hello, and welcome to episode 46 of the Fashion Unearthed podcast. I hope my voice today isn't too annoying for you. Being based in Melbourne means that winter is well and truly here and I'm on the tail end of recovering from a bit of a head cold. But I hope you can bear with me because today's episode is a goodie. But just quickly before I get to that a little reminder to get on my newsletter if you're a fashion business owner, as I'm planning on changing up the format and including some exclusive content, giving you even more insight into sustainability within fashion, as well as some practical insider tips from my 20 years in fashion. So head to belindahumphrey.com and sign up to that if you need help navigating the product development process in a sustainable way.


Okay, so today's episode is an extension I guess in a way of Episode 43. The episode where I went through some of the key focuses the denim industry have to be more sustainable. When I was trying to find a statistic on water use for a pair of jeans, there were so many variations ranging anywhere from 1500 litres right up to 8100 litres. In the course of me researching I also come across brands and businesses referencing, (in quotation marks) "It takes 20,000 litres of water to make the cotton for a T shirt or a pair of jeans" And I was really interested to dig into that a bit more particularly because Australian cotton is basically a brand itself here in Australia and I really wanted to understand how much water does it take to make a pair of jeans or T shirt. Now if you've been listening for a while, you probably know that the fashion world is a minefield full of misinformation, even for people who work in it. But thankfully, I found an amazing report done at the end of last year called Cotton: A case study in misinformation. And it was written by the Transformers Foundation, which I'll link to in the show notes on my website. And I highly recommend you downloading it and reading it for yourself. It is quite long, it's 137 pages, but the format is more like a magazine rather than an academic report.


The report draws from cotton experts such as farmers, the International Cotton Advisory Committee, the ICAC and The Textile Exchange just to mention a few with the goals of:

  • Training readers to become critical consumers of data and information using cotton's water and pesticide use as a case study
  • Debunk and pre bunk the most common myths about the cotton industry, showing how to vet claims and data and confront misinformation whenever you encounter it.
  • Gather and share publicly the best available sound data and context on cotton to use in place of misinformation.
  • And foster the cotton industry is consensus around the data contained in the report so that it's trusted and usable for the industry and the wider public.

With so much being taken out of context for a social media grab or the oversimplifying of issues, I think this is really important work. Plus a lot of the statistics I mentioned have been seen on very credible brands and websites. So I think it's a really big problem that needs to be addressed. Which is why I wanted to highlight the report in today's episode because I think it's been put together really well and it also sparks some conversation around where we're getting data from. They even anticipate that you will question what their motives are and they have a page in the report called Why should you trust us, which details the measures that they have taken to balance a perceived bias towards cotton, such as using primary data, and peer reviewed data where possible, as well as an independent and experienced fact checker, not employed by any industry association as well as their own.


So in the report, there are four main myths that they address. The first being cotton consumes 20,000 litres of water per kilogram of fibre. The second, 25% of the world's insecticides are used on cotton. Three, cotton is a water thirsty crop and four, organic cotton uses 91% less water than conventional cotton.


Today, I wanted to talk through some of their findings for the first one about cotton consuming 20,000 litres of water per kilo of fibre. But the other three are very interesting and I'm sure you've probably seen those quotes as well and like I said, I'd highly recommend you downloading the report which I'll share the link in the show notes in the podcast section.


But for today's episode, I wanted to focus on the findings of that first one about cotton consuming 20,000 litres of water per kilo of fibre. Firstly, they broadly agree that one kilogram of lint does produce a pair of jeans and a T shirt, depending on the size and weight of the garment. But according to the most recent data from the International Cotton Advisory Committee, as of 2020 Cotton uses 1931 litres of irrigation water or blue water, on average to produce one kilogram of lint. Globally cotton uses 6003 litres of rainwater or green water on average to produce one kilogram of lint. They then go on to try and find the source of it taking 20,000 litres. They explain the primary source of the 20,000 litres claim is often cited as the World Wildlife Fund, an environmental non-profit, from its 1999 report "The impact of cotton on freshwater resources and ecosystems". Coupled with the WWF cotton page, which from at least 2013 to late 2020 featured a large infographic saying "20,000 litres the amount of water needed to produce one kilogram of cotton equivalent to a single t shirt and a pair of jeans". This statistic was only recently taken down. However, even within this report, it states that cotton consumes between 7000 and 29000 litres of water withdrawals and it's unclear how or if this statistic morphed into the 20,000 litres figure. The Transformers foundation go on to say that the report's methodology isn't transparent, and appears to compare different sets of data which aren't disclosed and its findings aren't peer reviewed. They rate the claim as false and one that you shouldn't be using because it has no known primary source and is also missing key context. They write the claim is false and one that you shouldn't be using because it has no known primary source and is also missing key context as well as being outdated and inaccurate in modern context.


So you might be thinking well, what statistic can I use and what is accurate, they actually caution against using some of the statistics they find or quote has been current because of there being so many variables and needing so much context. Even within the language that is used, water consumption and use are very different terms and mean different things. Then there is the three types of water, green, blue and grey water. There's a great infographic on page 56 and 59 of that report that explains visually what the difference is. But green water is rainfall, basically, blue water is surface water from lakes and rivers or groundwater that is irrigated, and grey water is water used to dilute industrial pollution such as fertilisers and pesticide runoff to return water back to agreed upon water quality standards. Where the water is coming from and how it's managed is important when you're talking about sustainability and location is a big influence. You will be right in imagining that local water availability differs from country to country. Within the report they even state that 52% of all cotton is rain fed. But you can see just from that little snapshot, it gets complicated quickly and context is vital.


Going back to the numbers in the report, they give an example from the United States where cotton farmers in the southeast use 234 litres of irrigated water per kilogram of cotton compared to the farmers in the West who use 3272 litres of irrigated water per kilo. Bringing it back to Australia, Cotton Australia estimates "it takes around 600 litres of water to grow the lint for a 150 gram cotton t shirt. By way of comparison, Sydney Water reports that the average water use per person per day in Sydney is about 324 litres". They also report that "Australian cotton growers can grow one kilo of fibre with about 2400 litres of water. This calculation is made using estimated figures for Australian cotton production of six mega litres of water per hectare and a yield of 11 bales per hectare."


Cotton Australia didn't specify on the website whether this was green or blue water but the Transformers Foundation report tables a graph on page 64 that lists Australia as using 1757 litres of blue or irrigated water per kilo of lint. So it would suggest that irrigation plays a big part in Australian crops but levels of water withdrawals for irrigation in Australia are said to be regulated by our government to deliver sustainable water use from healthy river systems. Perhaps this is the reason that water use productivity by Australian cotton growers improved by 48% since 1992.


Now, I don't want to risk doing what the report says exactly not to do, which is oversimplify a very complicated issue. So in summary, don't use that statistic, which is 20 years old now, on your website and be cautious of using any statistics, global average ones in particular. The only instance where you might feel confident to use some statistics I would say is if you can trace back the cotton you're getting to the actual farm. Again, it really is worth the time to read and go through that report as even for me who's been in the industry for 20 years, it clarifies and brings to light, just how many variables there are when you're dealing with trying to calculate any environmental cost, from location, type of waters, government regulations, and even the size and scale of the farm.


But hopefully, that hasn't left you too bamboozled and I'd love to know if it's made you rethink some of the assumptions you have about materials and cotton in particular, you can email me at info@belindahumphrey.com, or direct message or DM me on Instagram @belindahumphrey_ again, a reminder that I will be planning on offering exclusive content to my newsletter subscribers. So make sure you're signed up to that and you can do that by heading to the website belindahumphrey.com And you'll find the links in any show notes on the website too, in the podcast section. Thanks so much for listening. See you next time.


Thanks for listening to the Fashion Unearthed podcast. If you want to get in touch head over to belindahumphrey.com or you can find me on Instagram @belindahumphrey_


Disclaimer: Whilst every effort is made to ensure that information is accurate at the time of recording, much like the fashion industry itself, this information may change. 




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