Cotton's thirst is the statistic that circulates most widely, but for many garments the larger water burden arrives later. Dyeing and finishing are where the volume concentrates.
Dye has to be dissolved to work
Textile dyes bond to fiber in solution. The fabric must be fully immersed so that dye molecules reach every part of every yarn.
That requires a bath many times the weight of the goods being colored, and the ratio between the two is a defining parameter of any dyeing process.
Reducing the ratio is possible but constrained, because too little liquid produces uneven color and the piece is rejected before it reaches a customer.
Fixation is incomplete by nature
Not all dye binds. A portion remains loose in the bath or clinging to the fiber surface, and it must be washed away or it will transfer onto skin and other clothes.
Rinsing therefore happens repeatedly, and each rinse is another full bath of water discharged carrying residual dye and process chemicals.
Darker shades and certain dye classes fix less efficiently than others, which is why deep blacks and vivid reds tend to be the most water-intensive colors to produce.
Preparation comes before color
Raw fabric carries natural waxes, seed fragments and any oils picked up during knitting or weaving. Dye will not deposit evenly over them.
Scouring and bleaching remove that material in additional wet stages, each with its own baths and rinses, before the first drop of dye is introduced.
Finishing after dyeing adds further steps for softness, wrinkle resistance or water repellency, and most of those are applied wet as well.
Field water and factory water differ
A large share of cotton's water is rainfall falling on a field, which would fall regardless of what is planted there.
Water drawn into a dyehouse is withdrawn from a river or aquifer, used, contaminated and then discharged, which places a different kind of demand on a watershed.
Treating both as a single number obscures the distinction that matters most for the communities living near the facility.
Where reduction is actually happening
Processes that dye with far less liquid exist, and some color polyester using pressurized carbon dioxide instead of water entirely.
Adoption is slow because retooling a dyehouse is capital-intensive and the savings accrue to a supplier working on thin margins rather than to the brand placing the order.
Brands that report progress here are usually describing a subset of their supply chain, which is why the claim is worth reading closely rather than accepting at face value.