Wastewater and Sludge Guidelines
The ZDHC Wastewater and Sludge Guidelines have been enhanced with new MRSL parameters, revised test methods, tighter wastewater limits, expanded sludge testing, and semi-announced sampling. Clarifications have also been made to wastewater flow rate requirements, discharge definitions, compliance expectations, MRSL detections, corrective action implementation, and terminology to improve consistency and support effective implementation of the Guidelines.
Updates July 2026
Limit values for wastewater flow rate of 15m3/day have been removed and turned into sample and report
There is no limit value for the flow rate. The 15m3/day are used as a differentiator for testing requirements of larger and smaller facilities.
Clarified that direct discharge definition excludes discharge into communal sewers in case those sewers are leading into a communal effluent treatment plant
The direct discharge category only applies to facilities who are directly discharging into natural water bodies or land.
Language added under Wastewater Quality Requirements
MRSL detections are not failures but an indication of the presence of restricted substances in the manufacturing process. Detections shall trigger a root cause analysis and, where required, corrective action plan.
Limits for MRSL substances are reporting limits. Detections over the reporting limits indicate that a certain substance is present in the wastewater. This is not a fail, but should trigger a root cause analysis and, if necessary, corrective action plan to ensure that no substances listed on the ZDHC MRSL are intentionally used.
Added language under Waste Water Quality Requirements
To conform with this guidelines, at least the foundational limit values must be met.
Foundational limits for conventional parameters, anions and heavy metals list the minimum requirements to comply with the ZDHC Wastewater and Sludge Guidelines. Values higher than foundational limits are therefore considered as a failure and lead to non-conformance with the guidelines.
Language added to the RCA/CAP section
Furthermore, the supplier is expected to complete the CAP within the indicated timeline and keep records to confirm the completion in the next testing cycle.
This change clarifies the expectation that suppliers who receive failures or alerts in the ClearStream Reports should not only perform a root cause analysis and setup a corrective action plan, but also implement the corrective action plan within the indicated timeline and document the implementation so it can be verified in the next reporting cycle.
Wording updated from microfibre to fibre fragmentation
In order to align with industry wording previously 'microfibre' updated to 'fibre fragmentation'.
October 2025
New parameters, updated test methods, tighter limits and new sludge testing groups for PFAS, flame retardants and phthalates, along with semi-announced sampling to improve consistency.
| Dimethylfumarate (DMFu) has been added as a new MRSL parameter with reporting limits of 50 ppb and test method with reporting limits of 50 ppb, respectively, for textiles and leather. |
| C.I. Basic Green 4 leuco base was added as a new ZDHC MRSL parameter with reporting limits of 500 ppb and test method with reporting limits of 500 ppb, respectively, for textiles and leather. |
| A new test method has been included in all MRSL parameters under group dyes—carcinogenic or equivalent concern and dyes—disperse (allergenic). |
| Tri-o-cresyl phosphate, trimethyl phosphate, trixylyl phosphate (TXP), decabromobiphenyl (DecaBB), tetrabromobisphenol A bis(2,3-dibromopropyl ether), and heptabromodiphenyl ether (heptaBDE) were added as new ZDHC MRSL parameters with 25 ppb as reporting limits for textiles and leather. |
| 2-Methoxypropanol was added as a new ZDHC MRSL parameter with 50 ppb as the reporting limit for textiles and leather. |
| Cresols (o,m,p) were earlier reported as individual substances, now as a sum of all, and the reporting limit is 1 ppb (sum of o,m,p cresol). |
| N, N-dimethylacetamide (DMAC), N-Ethyl-2 pyrrolidone (NEP), N-Methyl-2-Pyrrolidone (NMP), and N,N-dimethylformamide (DMFa) were added as new parameters, and a test method with a new reporting limit of “sample and report” was added. A special condition, applicable only for direct discharge facilities, states that if the detection is >5000 ppb in the untreated wastewater, these parameters must also be tested in the discharged wastewater/effluent. |
| Xylene was earlier reported as individual substances, but it is now reported as the sum of all, and the reporting limit is 1 ppb (sum of o,m,p xylene). |
| (Free) aniline added as a new ZDHC MRSL parameter with test method and reporting limit as sample and report. |
| D4 (Octamethylcyclotetrasiloxane), D5 (Decamethylcyclopentasiloxane), D6 (Dodecamethylcyclohexasiloxane) were added as a new MRSL parameters with test method and reporting limit as sample and report. |
| The perboric acid, sodium salt reporting limit for textiles and leather has been updated to 500 ppb, up from 100 ppb earlier. The test method remains the same. |
| Perfluorobutane sulfonic acid (PFBS), perfluorohexane sulfonic acid (PFHxS), perfluorodecane sulfonic acid (PFDS), perfluorobutanoic acid (PFBA), perfluorohexanoic acid (PFHxA) and related substances, perfluorodecanoic acid (PFDA), 4:2 fluorotelomer alcohols (4:2 FTOH), 6:2 fluorotelomer alcohols (6:2 FTOH), 8:2 fluorotelomer alcohols (8:2 FTOH), 10:2 fluorotelomer alcohols (10:2 FTOH) added as new MRSL parameters with new test methods and reporting limit set to 1 ppb respectively. |
| ,2-Benzenedicarboxylic acid, dipentylester, branched and linear, 1,2-benzenedicarboxylic acid, dihexyl ester, branched and linear, diisohexyl phthalate added as new ZDHC MRSL parameter and reporting limit allocated as 10 ppb for textile and leather. The test method remains the same. |
| Temperature absolute added as a new parameter under conventional parameters. |
| Foundational level limits (textile) updated for ammonium nitrogen to 5 ppm, which was earlier 10 ppm. |
| Foundational level limits (textile) updated for AOX to 2 ppm, which was earlier 3 ppm. |
| Foundational, progressive, aspirational level limits (textile and leather) updated for sulfite to 0.5 ppm from 2 ppm, 0.05 ppm to 0.5 ppm, 0.01 ppm from 0.2 ppm |
| New ZDHC MRSL groups (flame retardants, perfluorinated and polyfluorinated chemicals (PFCs), phthalates—including all other esters of ortho-phthalic acid), with new test methods and reporting limits for each parameter under the respective group, have been added for sludge testing for textiles and leather. |
| Semi-announced sampling for wastewater and sludge introduced. |
| Raw Wool scouring facilities included in the scope. |
| 5 metals tested in wastewater (arsenic, cadmium, chromium (VI), lead, mercury) which were earlier having limits at foundational/progressive/aspirational level limits changed to sample and report only for indirect types of discharge. |