Tap water, while suitable for drinking, is full of contaminants that can ruin experiments. It contains dissolved salts (ions like sodium, calcium, and chloride), minerals, and organic matter. A lab deionized water system works by passing feed water through specially manufactured ion-exchange resins. These resins swap out the dissolved salts for hydrogen and hydroxyl ions, which then combine to form pure water (H₂O). The result is a highly purified solvent that won't leave mineral deposits on glassware, interfere with chemical reactions, or skew sensitive analytical results in processes like High-Performance Liquid Chromatography (HPLC) or tissue culture.