ZDHC, the Zero Discharge of Hazardous Chemicals programme, is a brand-led initiative that aims to remove hazardous chemicals from textile, leather and footwear manufacturing. Brands ask about it because it shifts chemical control from the finished product to the mill: instead of only testing fabric for what is in it, ZDHC restricts which chemicals the mill is allowed to buy and use, and sets guidelines for the wastewater the mill discharges.
For a buyer, the practical point is that a product test and a ZDHC question are different things. A fabric can pass every REACH test while the dyehouse that made it is discharging untreated effluent, and ZDHC is the tool brands use to look at that.
The two main parts of ZDHC
The Manufacturing Restricted Substances List, the MRSL, lists chemical substances that must not be intentionally used in the formulations a mill buys, such as dyes, auxiliaries and finishing agents. It differs from a product RSL, which limits what remains in the finished goods. Chemical suppliers have their products assessed against the MRSL, and a mill that buys only conformant products can show that its inputs are clean.
The Wastewater Guidelines set out what a mill should test for in its effluent and sludge, and how often. Mills test with approved laboratories and share results through the ZDHC platform, where brands can see them. Together the two create a record of chemical inputs and outputs for each facility.
What brands actually ask for
- Confirmation that the mill or dyehouse is registered on the ZDHC platform.
- Evidence that chemical inputs are MRSL-conformant, often as a chemical inventory.
- Recent wastewater test results against the guidelines.
- Supplier training or assessment status under the programme.
What this means when buying from India
Large export mills in the Ahmedabad and Surat area with existing brand business are often already registered and can share results. Smaller dyehouses and printers, which often do the actual wet processing for a mill, frequently are not, and that is where the gap tends to be. Ask early, because a mill cannot become conformant between order and shipment. Where the mill subcontracts dyeing, ask for the dyehouse's status separately, since the mill's own registration does not cover a subcontractor.
ZDHC is voluntary and sits alongside, not instead of, legal requirements such as REACH and the CPSIA. The programme's lists and guidelines are updated, so confirm the current version your brand requires with your compliance team or an accredited lab. This is general information, not legal advice.
How we help with ZDHC
ZDHC conformance is a question for the mill, but we can ask it for you before the order is placed and pass on what the mill and its dyehouse share. On the product side we agree the test plan for your market, draw sealed samples from the bulk, send them to an NABL-accredited or international lab, and check the report against the spec before loading. We supervise the loading, update you weekly and offer a free 20-minute sourcing review if you want to map a supplier's chemical management before committing.