WC&P International
Home  |  Archive  |  Links  |  Media Kit  |  About WCP  |  Contact WCP  |  Glossary  |  Videos


Current IssueSeptember 02, 2015
Registered users login here to see extended content.
February 2004: Volume 46, Number 2

Witness for Certification -- Product Testing Is Controlled, But Not Confined
by Tom Bruursema and Rick Andrew

Summary: A new requirement announced in December by the state of California restricts “witness testing” in certification of drinking water treatment units. The following article speaks to this subject.

Product certification is founded on quality, independent, third-party testing to established protocols and standards. The criteria for quality and third-party independence are identified in standards, as established at the international level for all third-party product testing and certification organizations. These standards offer certifiers some flexibility in obtaining the required test data without compromising quality or independence. In turn, the same flexibility provides manufacturers with options in their product testing. One of these options is testing performed at the manufacturer’s facility.

In some instances, the certification representative may come equipped to perform the testing themselves at the manufacturer’s facility. The manufacturer can avoid the time and cost in product shipment, and the certifier can take advantage of other locations to perform their evaluations. At other times, the certifier may perform the testing but use the manufacturer’s test equipment. Still, another option is for the certification representative to witness the test as performed by the manufacturer’s representative using the manufacturer’s test equipment. NSF uses all of the above options and has guidelines that must be followed in each case to ensure quality and independence aren’t jeopardized.

International standards
The International Organization for Standardization (ISO) has established ISO/IEC CD Guide 67 (12-14-2000) Fundamentals of product certification. Section 7.4.2 of this guide (see Figure 1) clarifies the requirements of a testing program conducted at a manufacturer’s or supplier’s* facility.

Based upon the above guidelines, as used and accepted throughout the world, NSF has developed its own requirements that adhere to these criteria. The goal is to maintain the integrity of the NSF certification while optimizing flexibility to the manufacturer. In the case of the certification representative using its own equipment to conduct testing at the manufacturer’s facility, there are minimal requirements to be addressed by the manufacturer.

The primary issue would be the test environment at the facility and access to the product. A step higher in the level of requirements would be for those cases where the certification representative performs the testing, but relies on the manufacturer’s equipment. In these situations, the equipment and the facilities will both need to be evaluated. The final scenario, and the one that carries the largest number of requirements, is testing performed by the manufacturer using their own equipment while being monitored by the certification representative. This scenario is commonly referred to as “witness testing.”

Approval process
Before a manufacturer can conduct certification testing through the NSF witness test program, a pre-approval process must be completed. The steps of this approval process are as follows:

1. Witness test authorization is granted for specific types of tests. A laboratory may be approved to conduct only one type of test under the NSF/ANSI Drinking Water Treatment Unit (DWTU) standards or a multitude of tests. The scope depends on laboratory capability and their preferences. For example, a manufacturer may wish to gain witness test approval for Standard 42 for chlorine reduction testing only. Or, they may wish to expand into many other aesthetic or health claims.

2. The candidate witness test facility must first submit their test procedures and associated quality assurance and quality control (QA/QC) to NSF for review and approval.

3. The NSF lab manager will then review the candidate’s procedures for conformance to the requirements of the applicable DWTU standard and to NSF’s requirements for witness testing. It’s not uncommon to identify issues with laboratory capabilities during the procedure review stage. For instance, review of the test apparatus may reveal that bladder storage tanks must be installed in the manifold to maintain pressure at the beginning of “on” cycles. Or, it may be noted solenoid valves must be installed downstream of inline units for proper contaminant reduction testing.

4. The lab manager or an appropriate designee will audit the candidate witness test facility to approve laboratory apparatus, procedures, and instrumentation as being capable of performing testing in conformance with NSF requirements. Any laboratory deficiencies not revealed through the procedure review process are addressed during this on-site audit.

5. Any non-conformances in laboratory apparatus, instrumentation, procedures, and QA/QC must be resolved by the candidate witness test facility prior to authorization being granted.

6. The candidate laboratory is then approved for witness testing.

7. Approval is maintained based on conducting a minimum number of acceptable witness tests each year.

Witness testing process
There’s a degree of coordination necessary when conducting witness testing. As such, the witness testing process is a bit more complicated than the normal qualification test process of shipping samples to NSF. The following special considerations must be kept in mind to allow the requirements for witness testing to be met:

* Any witness testing must be arranged with NSF in advance.

* Designated NSF personnel must be present for the beginning and end of the test. If testing continues over a period of several days, NSF will also make one unannounced visit during testing. NSF employs many measures to ensure integrity of witness testing. These measures include, as examples, tagging the test units to verify that tampering hasn’t occurred. The NSF personnel also audit sample analysis, instrument calibration, gauge calibration, and other sensitive parameters during witness testing. In some cases, NSF personnel may work with witness laboratory personnel when conducting analysis relevant to the test. Depending on the specifics of the test, NSF may utilize other techniques to verify witness test integrity.

* All water samples with holding times greater than one day are shipped to NSF’s laboratories for analysis. Split samples may be collected by the witness test facility for comparison to results obtained at NSF. Examples of samples that would be analyzed by NSF include metals (such as lead analysis for Standard 53 - lead reduction), volatile organics (such as chloroform analysis for Standard 53 - VOC reduction), and extractable organics (such as 2,4-D analysis for Standard 53 - 2,4-D reduction). NSF provides sample containers and coolers for shipping samples in these cases.

There are also two caveats for witness test facilities to keep in mind regarding witness testing--witness testing for material extraction isn’t allowed, and witness testing isn’t allowed for five-year, re-qualification testing.

The California issue
On Dec. 8, 2003, the California Department of Health Services (DHS) released “Policy Memo #D-2003-01 (Revised) ANSI-Certified Testing Organization Product Listings in Lieu of Test Reports.” This document addresses witness testing as follows:

“Witness testing: The Department is not accepting witness testing at this time. We do not believe that ANSI approval of witness testing procedures provides the same level of test data quality assurance as independent laboratory testing. Product listings submitted in lieu of test data under this policy should not be based on witness testing.”

While NSF and ANSI believe that properly authorized, conducted, and monitored witness testing is valid for product certification, California DHS doesn’t. Manufacturers must keep this policy in mind when considering witness testing of any health claims on products to be marketed in California.

There are many advantages to having a variety of testing options, both to NSF and the manufacturers. Some of these options are available to virtually everyone while others are limited to only a very few manufacturers who are able to make the necessary investment in personnel and equipment. All the options offer the benefit of having more flexibility in the testing schedule. Some, such as the witness test program, can also reduce the overall expense of testing. These benefits are carried down to the consumer through shortened product launch cycles and the potential for reduced cost while, at the same time, ensuring the credibility of certification is preserved.

About the authors
Tom Bruursema is the general manager of the NSF Drinking Water and Wastewater Treatment Unit Programs. He has been employed by NSF for 18 years, serving in a number of technical and administrative positions. Bruursema holds a bachelor’s degree in medical technology and a master’s degree in general biology from Eastern University Michigan. He is an honorary member of the Water Quality Association, and serves currently on the WQA International Standards and Regulations Task Force. He can be reached at (800) 673-6275 or email: bruursema@ nsf.org

Rick Andrew is the technical manager of the Drinking Water Treatment Units Program at NSF International. He has been with NSF for five years, working with certification of residential drinking water products. His previous experience was in the area of analytical and environmental chemistry consulting. Andrew has a bachelor’s degree and master’s degree in chemistry from the University of Michigan. He can be reached at (800) 673-6275 or email: andrew@ nsf.org


Figure 1. Supplier testing

The following is from ISO/IEC CD Guide 67 (12-14-2000) Fundamentals of product certification:

7.4.2 Use of supplier’s testing facilities. The involvement of suppliers in the certification process is important in many respects. The suppliers are the first and principal addressees of the certification and their role should be as active as possible. Testing at the supplier’s laboratory may be central to the scheme, provided that the testing capabilities have been assessed and recognized as shown in the previous paragraph. Testing at the supplier may be attractive for various technical and economical reasons. For instance, it may be impractical or uneconomical to displace the test object from the supplier’s premises to the laboratories of the certification body. Moreover, testing facilities of the supplier may be “unique” or indeed more suitable than those of the testing body, owing to the higher degree of the specialization of the former. Finally, testing at a supplier’s laboratory may allow a better utilization of the related facilities with obvious benefits for the economy of the entire certification scheme. Testing at a supplier’s laboratory may be conducted in different ways with different degrees of involvement of the certification body and of the supplier itself. Two main possibilities exist, which are correlated to the extent of the recognition process. They are shortly reviewed as follows: Testing at supplier’s premises. The tests are carried out by the personnel of one or more recognized testing laboratories at the premises of the supplier for the purpose of issuing a test report or test certificate. Testing equipment may be those existing at the supplier’s work site or put in place by the testing staff. The supplier should appoint an appropriate person to be responsible for the operation of the procedure. During testing, a representative of the testing body should be responsible for the supervision and recording of all tests, and be present during testing. Supervised supplier testing--Tests are performed by the staff of the supplier using its test equipment within a suitable recognition agreement between the certification body and the supplier. Parts of the tests, properly selected, are witnessed by an assessor of the certification body. A number of clauses should be included in the agreement. These may concern suspension or withdrawal of supervised supplier testing, prohibition of advertising, etc.