Nanosilica-treated fabrics have a variety of properties, such as durability, water resistance, and specific surface characteristics. Due to that, many applications of those components are highlighted in literature. Some examples include waterproofing and water repellency, stain resistance, flame retardancy, improved durability, UV protection, improved comfort, antimicrobial properties, and textile coatings for electronics. These applications demonstrate how nanosilica-based treatments can enhance the performance of fabrics, making them more suitable for various specialized uses. In this work, a technical fabric with a mesh opening of 45 μm and an open area of 29.6% was surface treated. The treatments were performed by the dip-coating method using poly(dimethylsiloxane) (PDMS) and nanosilica at different concentrations. Optical microscopy (OM) images of the fabrics’ surface and water contact angle (WCA) measurements were carried out before and after the fabrics’ treatments. The results showed a significant increase in the water contact angle of the treated fabrics compared to the untreated ones. After treatment with PDMS (4 wt.%) and silica nanoparticles (0.1 wt.%), the fabrics reached WCA values of approximately 140°, demonstrating the effectiveness of the coating in enhancing hydrophobicity compared to the untreated fabric (WCA of 103°). OM images demonstrated a good uniformity and dispersion of the nanoparticles on the fabrics’ surfaces after the treatments. Untreated fabric was not able to separate water from oil, while all the treated fabrics demonstrated efficient oil/water separation, varying only flux rate, depending on the type of surface treatment. In conclusion, the oil/water separation was effective when surface treatments were applied to the fabrics’ surfaces.