Wastewater and Sludge Guidelines

Version 2 - Last updated 28 Oct 2025

The guidelines now include 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.

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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.