How we calculate
Every Green Petition tag shows three numbers: PET bottles, T-shirts and liters of water. They are estimates of the new material and the water that your towel did not need, because it was made from recycled fibers instead of new ones. Here is exactly how we get them, so you can check our work.
The short version: we weigh what goes into each towel, apply published figures for growing new cotton, use conservative assumptions at every step, and round down.
1. Water saved
Almost all of the water behind a cotton towel is used before the towel exists, in the field, to grow the cotton. Recycled cotton skips that step. So the water we count is the water needed to grow the new cotton that your towel replaced.
Step 1 · Water to grow cotton in Türkiye
A 2019 Ankara University study of Türkiye's main cotton regions (Şanlıurfa, Aydın, Hatay, Diyarbakır, Adana and İzmir, about 90% of the country's cotton) found a water footprint of 17,746 m³ per hectare in 2016 and 16,059 m³ per hectare in 2018. The average of the two years is about 16,900 m³; we use 17,000 m³ = 17,000,000 liters per hectare.
Step 2 · From field to finished towel
One hectare yields 2,000–4,000 kg of seed cotton. We use the high end, 4,000 kg, because a bigger harvest means less water per kilo, which keeps our number on the low side.
| Stage | Kept | Weight |
|---|---|---|
| Seed cotton from 1 hectare | — | 4,000 kg |
| Fiber (after ginning) | 35% | 1,400 kg |
| Yarn | 80% | 1,120 kg |
| Fabric | 85% | 952 kg |
| Finished towels | 85% | 809 kg |
17,000,000 liters ÷ 809 kg = about 21,000 liters per kilo of cotton in a finished towel.
Step 3 · Your towel
We work out your towel's fabric weight from its size and fabric weight (width × length × g/m²), take the share that is recycled cotton, and count the water needed to grow that much new cotton. Then we round down. Recycled polyester does not count toward water, and neither does organic cotton: organic cotton is newly grown, so it did use water.
Example, Delmor Fit (76 × 142 cm, 320 g/m²): about 345 g of fabric, 50% recycled cotton. That is roughly 3,600 liters of water. Its tag says 3,500 L.
What this number does not include: the water used to recycle, spin and weave our own fibers. That is small compared with growing cotton, and our fabrics are not dyed, which removes one of the most water-intensive steps in textile making. The figure also does not claim a measurement of your specific towel's supply chain; it is an estimate based on published averages.
Sanity check: a widely cited global study puts the water footprint of cotton fabric at around 11,000 liters per kilo (Chapagain et al., 2006). Our Türkiye-specific figure is higher because irrigation supplies about 96% of the water cotton uses here, and because we count losses from field to finished towel.
2. Recycled PET bottles
The polyester in our blends is made from recycled PET. We divide the weight of recycled polyester in your towel by the weight of a typical plastic bottle, about 20 g. The tag shows a lower, rounded figure.
Example, Delmor Fit: about 173 g of recycled polyester ÷ 20 g ≈ 8.6 bottles. Its tag says 7.
3. T-shirts' worth of cotton
Our cotton comes from pre-consumer fabric scraps: colored offcuts left over when clothes are cut in factories, before anyone wears them. We do not cut up used T-shirts. The T-shirt number is simply a way to picture the amount: it shows how many T-shirts' worth of cutting offcuts went into your towel instead of new cotton.
When the pieces of a T-shirt are cut from fabric, about 15% of the fabric is left over as offcuts, about 37.5 g per T-shirt. We divide the recycled cotton in your towel by that amount. The tag shows a lower, rounded figure.
Example, Delmor Fit: about 173 g of recycled cotton ÷ 37.5 g ≈ 4.6 T-shirts' worth of offcuts. Its tag says 3.
Why we round down
Averages hide variation: harvests, irrigation and factory losses change from year to year. Rather than claim the most impressive number, we choose the conservative end of each range, and the numbers printed on your tag are at or below what these methods give. If our assumptions change, we will update this page and say so.
Sources
Methodology and calculations: Özgür Usta, Textile Engineer, Founder of Green Petition.
- Engin, S. (2019). Türkiye'de Pamuk Üretiminin Su Ayak İzi [The water footprint of cotton production in Türkiye]. Master's thesis, Ankara University, Institute of Social Sciences, Department of Water Policy and Security. Advisor: Assoc. Prof. Dr. Gökşen Çapar.
- Chapagain, A.K., Hoekstra, A.Y., Savenije, H.H.G., Gautam, R. (2006). The water footprint of cotton consumption. Ecological Economics 60(1). Read the report ↗
- Ginning and processing yields: industry averages used by Green Petition.
Questions about a number on your tag? Write to us, we answer every message.