Jul 01, 2020

Interpreting Standards for Lead in Drinking Water Treatment Units

This article originally appeared in WQP July 2020 issue as "Sorting Through the Standards"

drinking water, lead standards, drinking water units

Ever since the crisis in Flint, Michigan, the issue of lead in our drinking water supply has been at the forefront of concerned minds across the nation. This is all for good reason. Lead has been shown to affect brain development in children and elevated lead levels in the blood have been linked to lower IQ. According to the U.S. EPA, lead is persistent, and it can bioaccumulate in the body over time. They also estimate that drinking water can make up 20% or more of a person’s total exposure to lead.

The current non-enforceable maximum contaminant level goals for lead in drinking water is zero. This is because lead is a toxic metal that can be harmful to human health even at low exposure levels. Regulations and guidance in the industry are constantly changing in response to this knowledge. In late 2018, the EPA revised its guidance on the 3Ts for Reducing Lead in Drinking Water in Schools and Child Care Facilities. This updated language loosely suggested 5 parts per billion (ppb) as a level that indicates the upstream plumbing is contributing toward the lead levels and that follow up and remediation should be performed. Many state, local and federal governments have since introduced or passed legislation reducing the maximum acceptable lead concentration in drinking water to 5 ppb.

As members of the industry, people often look to us for advice on which products are appropriate to ensure that they have safe drinking water. The vast amount of constantly changing information can be confusing to those even with years of experience. When it comes to the drinking water standards, the information can be similarly confusing since lead shows up in many different places for completely different reasons. Let us sort through the standards to see where lead appears, and why it is there in each case.


Understanding Each Standard

NSF/ANSI 53 Drinking Water Treatment Units - Health Effects. The NSF/ANSI 53 standard establishes the testing protocols and reduction requirements for lead removal performance claims. This standard is important for filters which intend to remove lead from the influent drinking water. This reduction is typically achieved through a specialty carbon or additive to be used in conjunction with another media. Most activated carbons are not able to reduce the amount of lead to required levels alone.

As a result of changing legislation, the 2019 version of the standard has reduced the pass/fail criteria for the lead reduction from 10 ppb to 5 ppb. Many certification agencies have already adopted or have plans in place to adopt and enforce this new level for certifications on both new and existing products.

NSF/ANSI 58 Reverse Osmosis Drinking Water Treatment Systems. The NSF/ANSI 58 standard is similar to the NSF/ANSI 53 standard regarding lead. It also establishes the testing protocols and reduction requirements for filters that remove lead from drinking water, and the pass/fail reduction requirements have similarly changed from 10 ppb to 5 ppb in the 2019 version of this standard. The main difference versus NSF/ANSI 53 is that NSF/ANSI 58 specifically addresses reverse osmosis (RO) membranes and systems as the title implies. 

NSF/ANSI 372 Drinking Water System Components - Lead Content. The NSF/ANSI 372 standard addresses the amount of lead content in any materials that come in contact with drinking water. This standard is directly in response to section 1417 of the Safe Drinking Water Act (SWDA) which prohibits the use of plumbing fittings, fixtures, solders, and fluxes which do not meet the definition of “lead free.” Lead free is defined in the act as “not containing more than 0.2% lead when used with respect to solder and flux; and not more than a weighted average of 0.25% lead when used with respect to the wetted surfaces of pipes, pipe fittings, plumbing fittings, and fixtures.”

The NSF/ANSI standard defines both the acceptable analytical procedures as well as the components of a product that are required to be tested. Specifically, any materials that have lead specified in their composition, or any materials that are more than 10% of the total wetted surface area of the certified system or component must be further evaluated for lead content. Outside of solders and fluxes, lead is typically found in brass and bronze, and those are the materials which often fail the testing.


Although manufacturers are required to comply with the Safe Drinking Water Act (SDWA), there is currently no federal requirement to obtain NSF/ANSI 372 certification. State and local legislations may require NSF/ANSI 372 certification for products sold within their jurisdictions, however. In general, certification to NSF/ANSI 372 is one of the easiest ways to ensure compliance to the SDWA.

NSF/ANSI/CAN 600 (Formerly part of NSF/ANSI/CAN 61) - Health Effects Evaluation and Criteria for Chemicals in Drinking Water. The NSF/ANSI/CAN 600 standard is referenced via NSF/ANSI/CAN 61 in many other standards under the material safety section, commonly known as extraction testing. Extraction testing is a required test for any certified filtration system, material or component to determine if the product itself is leaching any harmful materials back into the drinking water. This is important to ensure that certified filtration systems are not making the drinking water worse than if they were not there. 

The NSF/ANSI/CAN 600 specifically addresses the pass/fail criteria for the level of substances that may leach out into the drinking water, including lead. Currently, this level is also set at 5 ppb for most residential water filtration systems.

This standard may seem redundant when considered with NSF/ANSI 372, as both address the safety of materials contacting the drinking water. However, there is a need for both as NSF/ANSI 372 establishes the criteria to specifically comply with the SWDA, while extraction testing and NSF/ANSI/CAN 600 establishes the limits on lead actually leaching into the water. NSF/ANSI/CAN 600 also addresses many other substances beyond lead. The two standards are particularly important when considering the events that occurred in Flint; lead sat dormant and trapped in supply lines for many years until a water source change caused the lead to eventually be released from them.

Different products may be certified to any number of the above standards. For instance, a lead removal filter typically would be certified to NSF/ANSI 53 and 372, while passing the extraction levels defined by NSF/ANSI/CAN 600. A plumbing fitting, such as a faucet, typically would be certified to NSF/ANSI 372 and NSF/ANSI/CAN 61, which also refers to the extraction levels of NSF/ANSI/CAN 600. There are other standards in the industry that products can be certified to, as well. ASSE LEC 2006-2019 is a standard similar to NSF/ANSI 58, but is specific to point-of-entry RO systems. This standard still has a pass/fail level of 10 ppb for lead reduction, but is likely to be reduced to 5 ppb during the next revision. 

Each day, we continue to get a better understanding of just how large the scope of the lead problem is in our drinking water. It is also clear that without massive infrastructure improvements, the issue will continue to persist for many years. It is therefore important for members of our industry to have a firm grasp of all the standards which relate to lead, as those are the tools that help ensure we are collectively providing our nation with access to safe drinking water. 

About the author

Ryan Prince is director of product certification – water systems for IAMPO. Prince can be reached at [email protected] or 708.995.3321.