Drinking water—a vital part of our ecosystem—is often exposed to contamination through industrialization. Halogenated compounds, for example, trihalomethanes (THMs), are among the most common contaminants, being by‐products of water chlorination/treatment. The carcinogenic and health effects of these compounds have motivated scientists to work on the accurate detection of THMs down to 80 ppb in treated water. Here, a superhydrophobic syndiotactic polypropylene (sPP) nanofiber mat is used to preconcentrate THMs in environmental water samples, and subsequently, detect them using a well‐known colorimetric reaction chemistry. The reaction chemistry yields a visible red/pink chromophore under visible light absorption. This reaction occurs when the preconcentrated THM becomes trapped in the liquid phase of the reaction chemistry, on the surface of the sPP fibers. This fiber mat is electrospun in a way which results in a large water contact angle >150°—allowing the working sensitivity of the reaction chemistry to be heightened and lowering the detection limit. The resulting color change can be analyzed via a simple quantitative color intensity analysis utilizing widely‐available software, measuring the THM content in water as low as 0.8 ppb. This cost‐effective and selective method was incorporated into a portable device, enabling on‐site users to evaluate the quality of drinking water.