Do Carbon Filters Remove Lead?

Lead is one of the most common drinking water contaminants, and it’s also one of the worst. According to the EPA, lead exposure in tap water can cause nervous system damage, cardiovascular problems, reproductive issues, and more.

So, if you detect lead in your water supply, you should look to remove it as a matter of urgency – but can you remove lead with an activated carbon filter?

🪨 Do Activated Carbon Filters Remove Lead?

Generally, yes, activated carbon filtration can remove lead.

However, not all activated carbon water filters are intended to be used for lead reduction. Some AC filters can only remove around 10-40% lead, so they’re not sold as a lead removal solution.

There are a few factors that affect an activated carbon filter’s lead removal effectiveness, which we’ve discussed later.

In short, some activated carbon filters remove lead, but not all of them.

🔃 How do Activated Carbon Filters Remove Lead?

Activated carbon filters adsorb contaminants in drinking water. When water flows through the filter media, contaminants in the liquid, including lead, adhere to its surface and are unable to pass to the other side with water molecules.

How does the adsorption process work?

The extensive surface area and porous structure of activated carbon provides sites for molecules in the water to physically adhere.

Additionally, certain contaminants undergo chemical reactions on the carbon surface, forming chemical bonds.

Activated carbon works selectively, capturing specific impurities based on their size, polarity, and chemical properties. Lead is one of the contaminants that can be effectively adsorbed into an AC filter’s media.

🤔 How Much Lead Can an Activated Carbon Filter Remove?

Generally, activated carbon filters can remove 10%-99% of lead from water.

This percentage range is pretty broad because:

• Basic charcoal carbon filters typically can’t remove a lot of lead.
• Higher-quality activated carbon block filters generally have better lead removal capabilities.

Don’t assume that all activated carbon water filters can remove equal amounts of lead. Heavy metals and lead removal vary from one AC filter to the next.

📝 Factors Affecting an Activated Carbon Filter’s Lead Adsorption Abilities

Not all activated carbon filters can remove lead, and some can adsorb lead more effectively than others.

There are a few different factors that affect an AC filter’s ability to remove lead, including:

• Filter pore size & distribution – An activated carbon water filter with a well-developed pore structure and larger pores is generally more effective at adsorbing lead. The distribution of different pore sizes within the filter media also plays a role in accommodating lead ions.
• Presence of additional contaminants – High concentrations of other competing substances in the water may reduce the filter’s lead adsorption efficiency.
• Filter material – The types of materials used to make an activated carbon filtration cartridge might also affect its ability to adsorb lead. Some materials may have better adsorbent properties than others.
• Filter surface area – The larger the activated carbon filter’s surface area, the greater the opportunity for adsorption. A filter cartridge with a large surface area will usually remove more lead than a filter with a smaller surface area.
• Flow rate – The speed at which water passes through the activated carbon filter affects contact time between the lead particles and the carbon surface. Typically, a long contact time (such as in gravity-based filters) is best for efficient adsorption.
• Additional factors – The chemical composition of the filter media, the water’s pH and temperature, and the presence of organic compounds may also affect lead adsorption in an AC water filter.

📊 The Evidence: Studies on the Effectiveness of Activated Carbon for Lead Removal

Although we know a whole lot about water filtration through our 10+ years in the industry, we’re not chemists.

So, to support the theory that activated carbon can remove lead in drinking water, we searched for scientific studies and reports on AC for lead removal spanning back 20 years.

Below, we’ve shared some of the most comprehensive and helpful studies we found. We’ve linked to the sources for further reading.

The Potential & Effectiveness of GAC For Lead Removal

A 2007 study examined the potential and effectiveness of granular activated carbon (GAC) to adsorb and remove heavy metals, specifically lead and cadmium, from the prepared solutions. Scientists conducted a “fixed bed column test”, which replicated the actual condition of continuous adsorption in a water filtration process. The results demonstrated that GAC could “successfully remove” both lead and cadmium in the column test.

Lead Removal Using Coconut Shell Carbon

One of the most recent studies, published in Sustainable Energy Technologies and Assessments in 2022, evaluated the effectiveness of lead and cadmium adsorption using powdered activated carbon derived from coconut waste. The study concluded that activated coconut carbon is an “extremely promising technology” for removing heavy metal ions like lead due to the presence of carboxylic and hydroxyl, which have a strong attraction to metal ions.

Lead Removal Using Unlikely Forms of Activated Carbon

We read dozens of studies on the experimental conversion of unconventional materials (often waste materials), such as black cumin, date pits, pine cones, hazelnut husks, and coffee residue into activated carbon, and the lead removal capabilities of these materials. All the studies we came across concluded that these unlikely forms of activated carbon could effectively reduce lead – one 2015 study on the use of cultured grape waste as an AC filter material found that grape pomace activated carbons could reduce up to 98% of lead. These studies suggested to us that generally, activated carbon made from a variety of different materials can effectively adsorb lead.

How Lead Adsorption Efficacy is Affected by AC Properties

This 2005 study published in Chemosphere focused on how the chemical and physical properties of an activated carbon filter affected its ability to adsorb lead ions. It concluded that the surface area and textural characteristics of activated carbon influenced lead adsorption, and that increasing the surface area and the pore size of the carbon helped to promote more effective lead adsorption.

🔎 How to Know if an Activated Carbon Filter Removes Lead

The best way to know whether a carbon filter removes lead is to check for an NSF (National Sanitation Foundation) 53 certification.

If a water filtration cartridge has been certified to this NSF Standard for lead removal, it means it has been officially tested and proven to reduce lead down to a certain level.

Most manufacturers share certification information as a selling point for their products. You can also use the NSF website to search for a specific product to see if it’s certified.

Carbon water filters don’t have to be officially certified to remove lead, but certifications offer reassurance that a manufacturer’s claims are accurate.

Second-best to an NSF certification is third-party laboratory testing to NSF Standards.

If you can’t find any information about certifications or third-party testing, contact the manufacturer and ask for a datasheet to support their performance claims.