Durable Water Repellent (DWR) coatings are a common chemical treatment applied to the exterior of fabrics to enhance water resistance. This finish causes water to bead up into droplets and roll off surfaces, preventing it from soaking into the material. DWR is widely used on outdoor gear, clothing, and footwear, often paired with waterproof-breathable membranes to maintain performance in wet conditions. The safety of these coatings is important because the chemicals involved can break down and enter the environment and the human body over time.
How Durable Water Repellent Coatings Function
DWR coatings work by lowering the surface energy of the fabric, creating a hydrophobic surface layer. This is achieved by applying a chemical treatment consisting of microscopic structures to the textile’s fibers. When water contacts the treated fabric, the low surface energy prevents water molecules from spreading out and wetting the surface.
Instead of soaking in, the water maintains its spherical shape due to surface tension, forming beads that easily roll off the material. Preventing the outer fabric layer from becoming saturated, a process known as “wetting out,” is necessary. This allows waterproof-breathable membranes to function correctly by letting water vapor from perspiration escape.
Health and Environmental Risks of Legacy DWR Chemicals
Safety concerns surrounding DWR coatings primarily involve per- and polyfluoroalkyl substances (PFAS), chemicals traditionally used in their manufacture. Original DWR formulations often relied on long-chain PFAS, such as perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). These substances are environmentally persistent because their strong carbon-fluorine bonds prevent them from breaking down naturally, earning them the nickname “forever chemicals.”
Once released during manufacturing, use, or washing, these compounds can leach into soil and water systems, leading to widespread environmental contamination. They are known to bioaccumulate, meaning they build up in the bodies of humans and animals over time.
Scientific studies have linked exposure to these legacy PFAS chemicals to several adverse health outcomes. Concerns include potential disruption of the endocrine system and negative effects on the immune system, possibly reducing the body’s ability to fight infections. Research also suggests links between long-chain PFAS exposure and liver disease, kidney disease, and developmental issues in children. Their persistence, bioaccumulation, and documented toxicity prompted a global phase-out of PFOA and PFOS in most consumer products.
Navigating Safer, Non-Fluorinated DWR Alternatives
In response to the environmental and health risks of legacy PFAS, the textile industry shifted toward safer alternatives. The first transition involved moving from C8 (eight-carbon chain) PFAS, like PFOA, to shorter-chain C6 fluorinated chemicals. Although C6 compounds are less persistent and less likely to bioaccumulate than C8 chemicals, they are still fluorinated and remain an environmental concern.
The current trend focuses on entirely non-fluorinated DWR options, often referred to as PFC-free, which eliminate all PFAS compounds. These newer treatments are based on different chemistries, including silicone, hydrocarbon polymers, or plant-based waxes. These alternatives achieve water repellency without introducing persistent fluorochemicals into the environment.
A trade-off exists in performance, as non-fluorinated DWRs often do not repel oil and stains as effectively as older fluorinated versions. The durability of the water repellency may also be slightly lower, meaning these safer coatings require more frequent reapplication to maintain optimal performance. This shift represents a move toward greater environmental responsibility, accepting a modest difference in initial performance for a gain in safety.
Consumer Guidance on Use and Product Identification
Consumers can make informed decisions by actively seeking products labeled as PFC-free or PFAS-free DWR. Many brands use specific labeling, such as “PFC-free,” “PFAS-free,” or “PFCEC-free DWR” (Perfluorinated Chemicals of Environmental Concern) to indicate the exclusion of these substances. When shopping, look for hangtags or product descriptions that explicitly state the DWR is non-fluorinated.
Extending the life of existing gear and maintaining its performance minimizes environmental impact. DWR treatments, regardless of their chemistry, diminish over time due to dirt, abrasion, and repeated washing. Re-waterproofing garments at home using readily available wash-in or spray-on products certified PFC-free is a simple way to restore function.
Regular cleaning of DWR-treated items is beneficial, as dirt and oils can compromise the water-repellent surface. Following care instructions and using technical wash products helps prevent environmental release and ensures the coating continues to work effectively. By prioritizing maintenance and choosing clearly labeled alternatives, individuals can enjoy the benefits of water-repellent gear while minimizing exposure to chemicals of concern.