To apply for acceptance as a ZDHC Approved Wastewater Laboratory, the applicant laboratory must request approval for the type of discharge (Direct discharge, indirect discharge with pretreatment with sludge,  Indirect discharge with pretreatment without sludge,  indirect discharge without pretreatment and ZLD) listed in the ZDHC Suppliers Roadmap to Zero, chapter ZDHC Wastewater and Sludge Guidelines V2. A ZDHC Approved Wastewater Laboratory is automatically approved to test MMCF facilities. The approval is requested per location. In addition, the following requirements must be met:

• ISO/IEC 17025 accreditation must include methods relevant to wastewater or sludge matrices or leachate. If not present, the laboratory can not be approved

• You can select more methods per parameter to be approved. 

COVERAGE OF ISO 17025/PT:

• At least 50% of all (wastewater + sludge/leachate) conventional parameters should be covered by an accredited scope.

  • For wastewater conventional parameters, if accreditation is not available for a specific method, the laboratory must provide evidence of a successful proficiency test performed using the method for which approval is being requested (Exceptions: persistent foam does not need any accreditation/PT, temperature does not have a PT available, if not accredited, the calibration certificate of the thermometer is needed)

  • For sludge/leachate conventional testing, accreditation is needed for pH and cyanide. As for the remaining parameters (e.g., fecal coliform, paint filter test, and percentage of solids), the submission of a Standard Operating Procedure (SOP) or a declaration referencing the applicable standard method is accepted.

• ISO/IEC 17025 accreditation must cover all metals and MRSL parameters 

DEVIATION IN THE ISO 17025 ACCREDITED METHOD

It is possible to be approved even if:

• The accreditation refers to a different matrix.

• A substance is not within the scope of the accredited method, but can be tested using an accredited method. (special case: if a method is not indicated, but only the analytical technique AND the parameter is not under the scope of the proposed method for approval, a self-declaration to confirm that the specific parameter can be tested under the specific accredited method is needed)

Here you can find documents to be provided to approve equivalent methods.

POSSIBILITY TO USE METHODS NOT PRESENT IN THE GUIDELINES

• The test methods specified in the ZDHC reference documents—or equivalent methods*—must be used, except for colour and COD, for which only test methods included in the ZDHC Suppliers Roadmap to Zero, chapter ZDHC Wastewater and Sludge Guidelines V2 must be used.

• If an analytical technique only is mentioned, any method accredited with the analytical technique required is fine (even if in a different matrix). Forbidden to use a different analytical technique.

 *Equivalent methods will be approved on a case-by-case basis.

Equivalent method definition: A laboratory procedure or analytical protocol developed in-house or adapted from standard practices, which is not strictly identical to an internationally approved or ZDHC listed test method, but has been demonstrated through appropriate validation to yield results that are reliably comparable, in terms of accuracy, precision, sensitivity, selectivity, limit of detection, limit of quantification, and specificity, to those obtained by the reference or accepted method.

A few of the indicators used defining/understanding/evaluating such equivalency could be:

• Spiking recoveries in the matrix of concern (typically 70-120% is an acceptable range)

• Repeatability and reproducibility within 5% RSD values are acceptable.

• TOST (Two-one-sided-Students T) test can be applied using regression analysis. 

TRAINING

• The laboratory must follow, apply, and train personnel in the use of the ZDHC Suppliers Roadmap to Zero, chapter ZDHC Wastewater and Sludge Guidelines V2 and ZDHC Wastewater and Sludge Laboratory Sampling and Analysis Plan V3.0.

SUBCONTRACT

• Rules for Subcontracting Analysis
  The rules regarding the subcontracting of analyses are defined as follows:

  1. It is permitted to subcontract all and ONLY the conventional parameters.

  2. It is permitted to subcontract all and ONLY parameters included in the ZDHC MRSL.

  3. In the case of a mix of conventional, metals and MRSL parameters, the following limitations apply:

     • A maximum of 5 conventional parameters,

     • A maximum of 2 metals,

     • A maximum of 5 MRSL parameter families.

  4. If only one parameter belonging to an MRSL family is subcontracted, that parameter will be considered as representing the entire family for counting purposes.

• The counts will be performed regardless of the matrix: the same parameter subcontracted for different matrices will be counted only once.

• Parameters to be tested in the field cannot be subcontracted.

• Subcontracting may be accepted solely on the condition that the testing is performed in-house by the subcontractor and is not further delegated or outsourced to any additional external parties.

• The subcontracted laboratory may be either an affiliate or an external laboratory.

• Only one outsourced laboratory can be selected per parameter. If more than one subcontract is needed per parameters, please ask ZDHC via SPP internal communication. 

GROUP POSSIBILITY OF APPROVAL:

Laboratories that are part of the same group using the same method in all the locations, can contact ZDHC (quality@zdhc.org) for more information regarding approval rules.

LOQ/LOD approval:

LOQ approval rule:

• LOQ must be equal to or lower than the Reporting Limit

• If there is a difference between the reporting limit of textile and leather, the reference Reporting Limit is the lower one.

• For Conventional and Metals the reference reporting limit is the aspirational ones.

Please note in certain situations, ZDHC may request additional information and documentation or carry out specific evaluations, which may include derogations on certain requirements or acceptance of equivalent quality assurance criteria, to grant a fair, consistent, high-quality implementation of the ZDHC Suppliers Roadmap to Zero on a global scale. If any extra fees are associated with this evaluation, the laboratory will receive advance notice.