In exhaust dyeing, which is in fact the most popular method, dyebath is not exhausted completely; in most cases, only substantial exhaustion is achieved. This unexhausted dye alongwith auxiliary chemicals pollute natural water bodies, when discharged. Most of the dyes and chemicals are highly toxic, even a few are non-degradable. Few chemicals pollute air in shop-floor too. The nature of waste water generated from drainage of baths is typical in nature and varies from one dye–fibre system to another.