RO Systems and Lead Reduction
By Rick Andrew
In January, this column reported on an update to the requirements in NSF/ANSI 53 for the lead reduction claim. Essentially, the Joint Committee on Drinking Water Treatment Units revised the pass/fail criteria for lead reduction from 10 μg/L to five μg/L in the effluent (filtered) water. This change was precipitated by regulatory developments regarding lead in drinking water. In March 2019, Health Canada lowered the national regulatory maximum allowable concentration of lead in drinking water from 10 ppb to five ppb.
The European Union has also proposed a revision to its Drinking Water Directive to lower lead concentrations to five ppb. The World Health Organization and other public health organizations have concluded there is no safe level of lead and that even low concentrations can cause adverse health effects, especially for infants and children. Several states are seeking to reduce regulatory levels for lead in drinking water to five μg/L.
Revisions to NSF/ANSI 58
Basically, the same change made to NSF/ANSI 53 has also been made to NSF/ANSI 58. The Joint Committee on Drinking Water Treatment Units revised the pass/fail criteria for lead reduction in NSF/ANSI 58 from 10 μg/L to five μg/L in the effluent (RO) water.
The influent challenge (raw water) concentration of lead remains at 150 μg/L, which means that under the new standard a higher treatment efficiency for lead is required (see Figure 1). Aside from the change in the requirement for lead reduction, the test protocol remains unchanged. This protocol continues to be a seven-day test of two test units with any pre- and post-filters removed or bypassed such that the efficiency of the RO membrane is being evaluated.
The test units are operated under a variety of conditions over the seven days, designed to evaluate real-world, end-use scenarios, including a two-day stagnation period in which no product water is withdrawn from the test units. There are 13 sample points during the test in which a sample of the influent challenge and a sample of the effluent water from each test unit is collected and analyzed for lead concentration. The average effluent sample lead concentration, as well as 90 percent of the individual effluent water samples, must meet the requirement of a maximum of five μg/L lead.
Considerations regarding the change
As this change was being proposed and evaluated by the joint committee, the impacts of the change were being evaluated. Test results were reviewed to determine whether previously tested RO systems had reduced the lead challenge to the proposed new level of five μg/L or lower. This review determined that most of the previously tested RO systems did indeed meet the proposed new criteria for lead reduction, making the impact of such a change a relatively minor one. This review of data and conclusion of minor impact on the industry provided reassurance to the joint committee that making this change would be beneficial in terms of public health and not disruptive for RO system manufacturers.
Cooperation among stakeholders
The NSF Joint Committee on Drinking Water Treatment Units is comprised of 28 voting members and 80 observers who offer input and expertise during the standard development process. Its activities are facilitated by NSF’s standards development group. The joint committee follows the American National Standards Institute (ANSI) process, which is designed to ensure openness, balance, consensus and due process for all stakeholders. These stakeholders represent the interests of consumers, water industry manufacturers and state and federal health and environmental agencies in the US and Canada. They come together through the ANSI consensus process to cooperate, provide expertise and work in the interest of protection of public health, while taking into account technological and manufacturing capabilities. Their cooperation is critical to the success of the standards development process.
The revised standard was also ratified by NSF’s Council of Public Health Consultants, which includes representatives from the US EPA, Health Canada and the US Centers for Disease Control and Prevention (CDC). This ratification is a last step for all standards developed by the joint committee to provide ultimate assurance that the standard is protective of public health. The result of this cooperation, in this particular case, is a standard which is more protective of public health, while causing minimal disruption for the manufacturers producing RO systems that conform to the standard.
About the author
Rick Andrew is NSF’s Director of Global Business Development–Water Systems. Previously, he served as General Manager of NSF’s Drinking Water Treatment Units (POU/POE), ERS (Protocols) and Biosafety Cabinetry Programs. Andrew has a Bachelor’s Degree in chemistry and an MBA from the University of Michigan. He can be reached at (800) NSF-MARK or email: Andrew@nsf.org