Phosphate-based water softeners are widely used in municipal systems, industrial water treatment, and some residential applications to control scale, corrosion, and metal deposition. They typically rely on orthophosphates and polyphosphates (such as sodium or trisodium phosphate), dosed into water to sequester calcium and magnesium. Production is closely tied to the broader phosphates industry, which serves fertilizers, detergents, and industrial chemicals. Global water softener market value was about USD 2.9 billion in 2023 and is projected to exceed USD 5 billion by 2032, with phosphate-based chemistries comprising a significant share in many regions.