Dying a shirt requires 25 liters of water. And a lot of harmful chemicals. Which is why it's good practice for any clothing manufacturer to look into creating safer methods. The CO2-based DryDye technology that Adidas has started using doesn't require a single drop of H2O.
How is this done? The fabrics and chemical dyes are placed in a large sealed chamber and CO2 is pumped into a pressure of about 74 bar. The tank is heated to 88 degrees fahrenheit at which point the CO2 behaves like a gas and a liquid allowing the colored dyes to permeate the fabrics without the use of excessive chemicals.
The DryDye process uses about half the chemicals as traditional water-based dying methods, and requires about half the energy too. Adidas has already made 50,000 shirts using this safer process this summer.