All that shipping around must completely offset the gains of the sustainable alternative to cotton.. though i guess it would do the same journey even with cotton.
Cotton farming has had a devastating effect on drainage basins across the world.
http://wwf.panda.org/about_our_earth/about_freshwater/freshw...
Closer to 10,000kg for 1kg of cotton if these Guardian statistics [0] are correct. While still quite wasteful - it is half as wasteful as you claimed (but still more wasteful than nearly everything)
[0] Data https://www.theguardian.com/news/datablog/2013/jan/10/how-mu...
However, suppose I use 10,000 L of water to irrigate my cotton plot. A lot of this water is lost to evaporation and transpiration. A little bit is bound up in the non-harvest-able parts of the plant too. However, none of this water seems like it's really "lost"--it eventually comes back as rain or snow, right? If we're not spending tons of energy moving the water around, this doesn't seem too awful. The worst possible outcome seems like it would involve the water evaporating and then returning as rain over the sea, which would make it more expensive to reuse as fresh water.
On the flip side, I can imagine that some water is also contaminated by the processing in a way that makes it expensive or impossible to reuse. That seems much worse.
It could be worth weaving in Morocco rather than China, but I guess the sewing is only in Morocco to cut the lead time between sewing and selling in Europe.