Last reviewed: September 2026
Sodium hexametaphosphate is a polyphosphate used in selected water-treatment programs. Polyphosphates can sequester dissolved iron and manganese, helping limit oxidation, precipitation, discoloration, and staining under suitable water conditions.
Sodium Hexametaphosphate
Sodium Hexametaphosphate and Polyphosphate Treatment
Common applications
- Iron and manganese sequestration in eligible source waters
- Control of discoloration and mineral staining associated with dissolved metals
- Formulated phosphate programs selected for specific water-quality objectives
Process and monitoring considerations
The U.S. Environmental Protection Agency distinguishes polyphosphate sequestration from orthophosphate corrosion control: polyphosphates alone are not considered effective for lead and copper control. Treatment selection should account for source-water chemistry, treatment goals, contact conditions, distribution-system behavior, and applicable regulations. Different polyphosphate species can behave differently, so feed rates and performance should be verified through monitoring rather than a universal dosage.
Compare polyphosphate and orthophosphate treatment goals.
Contact WSU about sodium hexametaphosphate availability and delivery.
Source: U.S. EPA, Why do water systems add phosphate to drinking water?
