The desire to regulate forever chemicals, often categorized as PFAS, has dominated the water industry conversation for much of 2023. In February, the European Chemicals Agency (ECHA) published a proposal that would heavily restrict the manufacture of over 12,000 of these chemicals. In March of 2023, the U.S. Environmental Protection Agency announced the proposed National Primary Drinking Water Regulation (NPDWR) with limits for PFAS materials in drinking water.
These restrictions focus on both production and abatement to reduce the exposure to the toxic effects of these materials in the community. PFAS can be present in our water, everyday products, and environment, including in the following:
- Public and private drinking-water systems.
- Soil and water near landfills and other hazardous-waste sites.
- Manufacturing facilities that produce or use PFAS.
- Food sources, such as fish or dairy from exposed livestock.
- Household and personal care products.
According to the U.S. Centers for Disease Control and Prevention, most people in the United States have been exposed to PFAS at low levels. However, some have already been exposed to elevated levels of PFAS over an extended period of time, often from drinking-water sources, which leads to long-term health issues.
Distinctions in the PFAS Chemical Families
PFAS refers to per- and polyfluoroalkyl substances, a group of chemicals made up primarily of carbon and fluorine, with a few other elements. Often labeled as forever chemicals, PFAS are characterized by a chain of carbon and fluorine atoms with strong bonds, making them difficult to degrade.
They are classified into two groups: polymers and nonpolymers. Polymers are believed to be relatively safe, as they are chemically stable under standard pressure and temperature. They are found in nonstick cookware, waterproof clothing, and other everyday items. Polytetrafluoroethylene (PTFE) falls into this category of PFAS materials.
Figure 1: Categories of PFAS materials.
Nonpolymers are likely to cause health problems and can be long- or short-chain substances. The long-chain materials are widely banned around the world and include perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). Short-chain materials are newer and include 6:2 fluorotelomer alcohol (FTOH), GenX, and C6. Although not widely banned, they are thought to pose health risks. These are the target of the NPDWR, which provides an expressed limit on PFOA and PFOS and a hazard index for a combined presence of other toxic PFAS materials.
Table 1: Proposed NPDWR on PFAS
These regulations aim to reduce the exposure and adverse effects of these materials on the population. However, current commercially available test methods are unable to detect below the level of one part per billion—and the proposed regulations aim for parts per trillion. As the water industry moves to develop new test methods to meet these proposed regulations, many manufacturers are preparing for the impact on customers and product lines. The treatment of the incoming or feed water in residential, commercial, and public buildings is meant to ensure both compliance and safety of the water supply.
Existing Methods to Address PFAS
Coming into the Home
The two most common systems to filter PFAS at point of entry are reverse osmosis (RO) and granular activated carbon (GAC) systems. They both provide protection from the primary targets of the ECHA and NPDWR, as well as other water contaminants. Typically, reverse osmosis provides a higher level of filtration by removing contaminates that create bad taste and odor. However, in most applications, the improved performance comes with a reduction in flow rate, higher cost, and significant wastewater generation.
Table 2: Contaminant Removal of Common Point-of-Entry Treatment Systems
RO systems will address other contaminants, such as heavy metals and dissolved solids, while also removing minerals in the water. However, during this process, up to 65 percent of the water is expelled as waste, making these systems problematic for areas struggling with drought or water scarcity.
GAC is a more cost-effective way to improve water quality, mainly by removing organics and reducing the level of other particulates in the water. Activated carbon has a much lower pressure drop than a reverse osmosis system, which is why it is the common choice when the end-user is not concerned about the odor or taste of the incoming water.
While these methods remove the trace PFAS chemicals present in the incoming water, they also remove some of the protective chemicals, such as chlorine, that ensure the potability of the water throughout the home. Removing chlorine leaves the home system at risk for opportunistic property piping pathogens.
Addressing the Risk of Opportunistic
Property Piping Pathogens
Property piping is the portion of the water distribution system beyond the property line in both residential and commercial buildings. These pipes are prone to biofouling because there is a high surface-to-water ratio with intermittent stagnation and warming cycles. This creates an environment that is very attractive and friendly to microbial growth. The chorine present in most municipal water supplies ensures the control of these pathogens. However, as chlorine is removed by RO or GAC systems meant to address PFAS chemicals, the piping is left vulnerable to growth.
The most common target pathogens in these scenarios include Legionella pneumophila, Mycobacterium avium, and Pseudomonas aeruginosa, posing the most risk to immunocompromised and the very young and very old. Integration of ultraviolet (UV) disinfection into these water systems provides an added layer of protection against the microbial growth and presence in the resulting drinking water.
Tests performed by the University of Colorado Boulder in 2018 showed that a UVC LED-based point-of-use (POU) disinfection system was successful at reducing the presence of Legionella at various flow rates (Figure 2). The same design principles from the POU reactor tested in 2018 can be used to scale to higher flow rates as the performance of UVC light emitting diodes (LEDs) continues to improve in power output, lifetime, and wall plug efficiency. As GAC does not fully remove bacteria, viruses, and cysts, incorporating UV after treatment ensures the water remains safe for consumption at the point of use or dispense.
UVC LED-based systems like the one tested provide a compact, durable, effective, and energy-efficient method to add UV protection into existing systems. With lifetimes now in the tens of thousands, these solid-state light sources provide maintenance-free disinfection that lasts the lifetime of most household appliances and commercial water dispensers. This also makes the technology feasible for other hard-piped dispensers, such as coffee machines and ice makers, for which UV lamps pose ongoing maintenance challenges.
Figure 2: Disinfection performance in greater than 4 log reduction shown in data captured from UVC LED-based water disinfection reactor testing performance on Legionella at various flow rates. Source: University of Colorado Boulder, Linden Research Group, 2018.
In addition, as more points of dispense become electrified to incorporate smart-home features, the inclusion of a UVC LED module in faucets or shower heads—known for aerosolizing Legionella— becomes more practical.
We’re seeing the new PFAS regulations drive an increase in global installations of point-of-entry water treatment systems across residential, commercial, and public environments. While providing a proven method to address water quality coming into the building, this can expose the property piping to additional risks of microbial growth. UVC LEDs provide a compact, easy-to-integrate approach so equipment manufacturers can provide a total solution that meets PFAS regulation requirements without compromising water quality.
Figure 3: Illustration of residential application of common water-treatment technologies.
As the industry looks at how to adapt to these new standards, the opportunities for integrating UVC LEDs in additional locations within the system continue to emerge. A comprehensive technology package utilizing UVC LEDs and commercially available filtration technologies can cost-effectively ensure drinking water is free from residual chemicals, PFAS, and microbial contaminants.
About the author
Patrick Aigeldinger is a director of product management responsible for global product and business development activities at Crystal IS, an Asahi Kasei company and a U.S.-based manufacturer of high-performance UVC LEDs. He holds a degree from Millersville University of Pennsylvania in industrial engineering and completed his MBA at Villanova University.
About the company
Crystal IS is an Asahi Kasei company and a U.S.-based manufacturer of high-performance UVC LEDs. UVC LEDs integrate into OEM products to disinfect water, surfaces, and air in various applications, or as light sources for sensing in numerous scientific and industrial instrumentation applications, such as drinking water, life sciences, and health care.