Understanding NSF Certifications

October 17, 2018

Lead is a serious problem when it comes to drinking water. It impairs mental development in children and causes a range of health problems. That’s why Congress passed laws requiring lead-free plumbing components -- enter NSF certifications.

Lead in drinking water

Alloyed with other metals such as brass and copper, lead improves cast-ability and machineability. It also enhances the ability of a metal to handle thermal and mechanical shocks. Unfortunately, though, it leaches out into water flowing through or over parts containing lead. This happens faster when the water is hot or acidic, but it’s still an issue with cold water.


Congress passed the Safe Drinking Water Act in 1974 to regulate and restrict the substances in drinking water. In 1986, it was amended and reauthorized, requiring that components used in potable water systems be lead-free. At that time, “lead-free” meant less than 8 percent lead.

In 2014, the Reduction of Lead in Drinking Water Act took effect. This introduced a limit of 0.25 percent lead in “lead-free” plumbing components. However, components that will not come into contact with drinking water are exempt from this requirement.

Implications for contractors and the plumbing industry

The RLDWA means you must not use any components using more than 0.25 percent lead in any system that handles drinking water. However, it’s acceptable to use lead-containing components in other systems: heating, waste water, and toilet-flushing systems can all use components made partly from lead. The same goes for steam and gas-service systems.

This raises two questions:

  1. What special considerations are needed for lead-free components when designing a plumbing system?
  2. How do you recognize when a component is lead-free?

Design considerations

Lead-free components need particular care regarding alignment and temperature changes. Follow the old design methods and you risk cracking. The simplest fix or workaround is just to avoid close-coupling components. Put as much distance between each one as possible.

Recognizing when a component is lead-free

The National Sanitation Foundation operates a certification scheme. There are two standards that plumbers need to know about: NSF 61 and NSF 372.

NSF 61 addresses a range of materials used in plumbing components, not just lead. Certification to this standard shows that a component is unlikely to put any metal into the water.

NSF 372, which came into effect in October 2013, applies specifically to lead. Being certified to this standard verifies that a component incorporates less than 0.25 percent lead.

Plumbing components sold for use in drinking water systems must be certified to one of these standards and will carry appropriate markings.

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