Lead in drinking water is a growing concern for households and communities across the U.S. The good news is that a wide variety of treatment systems can address this issue, with options available to meet each unique situation. Revisions to the Environmental Protection Agency’s Lead and Copper Rule has reignited urgency around replacing lead service lines.  But disturbing service lines that have been in place for years can mobilize sediment that has built up in the pipes, or it could dislodge scale that has formed on the line’s surface. These sediments and scales can contain extremely high levels of lead, and it can end up in your plumbing system and at your faucet.

The revised Lead and Copper Rule also prompts schools and daycares to test their water systems for lead. Many of these facilities had never tested for lead and so now are discovering problems they didn’t know they had. 

These developments, and the media attention they’ve sparked, are driving renewed interest in residential and commercial drinking water treatment technologies that can remove lead. For plumbing, heating, and cooling professionals, understanding treatment technologies will play a crucial role in helping customers choose the right solution and ensuring effective performance. 

Filters

Point-of-Use (POU) filters are one of the most commonly used technologies for lead. However, it’s important to understand that not all filters are designed to remove lead. The EPA recommends selecting filters that are certified to remove lead in accordance with NSF/ANSI Standard 53 (Drinking Water Treatment Units – Health Effects), and also certified to remove Class 1 particulates in accordance with NSF/ANSI Standard 42 (Drinking Water Treatment Units – Aesthetic Effects). 

Because these certifications can be difficult to understand, the EPA has published a handy tool to help identify filters that meet these requirements. You can find it online.

The EPA recommends these two certifications for filters because lead is commonly found in drinking water in two forms: the dissolved element (dissolved lead) or a suspended particle (particulate lead). 

Certified filters rely on two primary mechanisms to remove lead. Dissolved lead, and even some of the very small particulates of lead, are captured in pore spaces within the activated carbon. This process is often enhanced with additives in the carbon, like ion-exchange media that specifically target lead. Large particulate lead is captured by size-exclusion. These larger particles never make it into the interior of the carbon filter, but instead accumulate on the surface of the carbon, inside the disposable filter cartridge. 

Certified lead filters come with a capacity rating, based on the number of gallons of water containing 150 ug/L of dissolved lead that can be effectively treated before pore spaces in the carbon run out of room to capture more dissolved lead. Since most particulate lead is captured by size-exclusion, especially the larger particles, the capacity limitation does not apply to particulate lead. The filter will continue to capture those particles indefinitely, until it plugs due to the buildup of particulate matter. At that point, the flow rate will decrease, signaling the need for replacement.

Certified filters offer a cost-effective and user-friendly solution for reducing lead in drinking water. These systems are available in a variety of formats to suit different installation preferences and needs:

Pitcher filters - which use gravity to drain water through a filter and don’t require any plumbing. 

Faucet-mounted filters - which attach directly to a faucet in place of the aerator. 

Under-counter systems - higher capacity units plumbed into a separate faucet used only for dispensing water intended for drinking or cooking. 

Hybrid or cross-over models -  that fall somewhere in between these three options, such as counter-top systems that can be plumbed into a faucet to facilitate easier filling using a diverter valve. 

POU filters for lead also tend to include an end-of-life indicator, such as a light that changes color to tell you when it is time to change out the cartridge. This feature supports proper maintenance, which is critical to ensure the performance of any water treatment device. 

Beyond the certified capacity, filters will be rated to provide specific flow rates. A typical faucet-mounted filter will operate at around 0.5 gallons per minute, while a typical pitcher filter will be rated at around 2 gallons per day. If higher flow rates are needed, an under-counter filter may be a better option. 

It’s important to understand distinctions in reducing different types of lead to make sure wholesalers, installers and consumers select the appropriate treatment products.

Particulate testing

While the certification testing for lead under NSF/ANSI Standard 53 includes both forms of lead, the additional certification testing for Class 1 particulates under NSF/ANSI 42  provides additional assurance that the filter is effective with particulate lead. 

However, the particulate lead testing under NSF/ANSI 53 is much more rigorous than the Class 1 particulate test under NSF/ANSI 42. Therefore, a filter certified under NSF/ANSI 53 should also pass the Class 1 particulate test, but the reverse is not guaranteed. 

Reverse Osmosis (RO) is another technology that can be effective for lead removal  at the Point of Use. Installing POU treatment provides two advantages:

Targeted treatment: Units are only treating water used for drinking and cooking, which is less than 1% of the overall water usage in a typical home. 

Final barrier protection: POU treatment has the advantage of capturing any contaminants that are picked up as the water travels through the household plumbing. 

RO systems can be designed and configured to remove a very broad range of contaminants, including organics, inorganics, and metals. For example, a POU RO system might be a better option for someone on a private well who is concerned about arsenic, lead, pesticides and nitrates, while a POU filter might be a simpler option for someone on a municipal water supply, where lead is the primary concern. 

RO systems operate through size exclusion. A semi-permeable membrane allows water to pass through to the treated side of the membrane, while flushing contaminants out through a reject line. Therefore, whenever the system is actively treating water, it is also sending some reject water down the drain. To minimize this, these systems are typically plumbed into a separate faucet only used for drinking and cooking.

Also, note that treated RO water – now with a low pH and low in dissolved solids - tends to be corrosive to metals. Therefore, plumbing downstream of the RO system should be plastic and lead to a non-leaded faucet. 

POU RO systems generally come with a pre-filter, which protects the membrane from chlorine and sediment, and a post-filter that polishes and improves the taste of the treated water. The pre and post filters will likely need to be replaced once or twice a year, while a typical membrane module will last 3 to 5 years. 

Some POU RO systems also come with end-of-life indicators, although this option is less common than in POU filters. 

And like filters, not all RO systems are designed to remove lead. Look for RO systems certified to NSF/ANSI standard 58 with a lead removal claim. 

Correct line pressure

Line pressure is a critical factor that impacts the performance of RO systems, and this information will be found in the product literature. If line pressure at the installation site is lower than specified in the literature, you may need a pump to increase the line pressure in order to achieve adequate removal of contaminants. This is valuable information for distributors to include with the product specifications, so that installers can determine in advance whether or not they will need to buy a pump. 

Another important specification for RO systems is the certified daily production rate for the system, measured in gallons per day. Installers should beware that some manufacturers will advertise the daily production rate of the membrane, which is misleading because it is not reflective of the gallons that the system will produce once installed. The actual daily production rate can be verified by checking the website listing of the certification body. 

Whole-house point-of-entry options for lead removal include both filtration and reverse osmosis. Whole-house filtration systems will be capable of delivering much higher capacity and flow rates than their POU counterparts. These systems can have a very long-life span, after which the entire tank will need to be swapped out with a new tank containing fresh media. During the lifespan of the system, the media will require periodic backwashing. It is important for distributors to include the backflush flow rate in the specifications because installers need to know whether the water supply is capable of providing that flow rate, especially if the water supply is a private well. 

Since RO systems can create corrosive water, installers will need post-treatment systems – such as a calcite filter - to re-adjust the pH and to re-mineralize the water. 

Several key specifications that installers should be aware of regarding whole house systems:

Maximum rated flow rates: Needed to comply with plumbing code sizing requirements. 

Pre-treatment needs: Vary by system and water supply but commonly include hardness reduction, iron and manganese removal, or sediment filtration. UV systems may be needed either as pre-treatment to protect the systems if the water supply is contaminated, or as post-treatment to prevent the buildup of biofilm in the premise plumbing. 

An exciting new option with whole-house systems is connectivity. Smart features can message a service provider to indicate maintenance is needed, ensuring a  continuous supply of high-quality drinking water.  

Whole-house systems commonly do not carry performance certifications for contaminant reduction because the cost of testing large-capacity systems with high flow rates is prohibitive. At a minimum, they will need to comply with the material safety requirements in NSF/ANSI/CAN standard 61 in order to meet many of the state and local plumbing codes. Material safety certifications ensure the product will not leach anything dangerous when it is in contact with water. 

Eric Yeggy is the Water Quality Association’s technical affairs director, and Bryanna Poczatek, WQA, is the technical affairs manager.