Overview
EN 1199:2005 is the CEN (European) standard that specifies characteristics, purity requirements and test methods for disodium hydrogen orthophosphate (also known as sodium phosphate, dibasic) when used for the treatment of water intended for human consumption. The standard covers identification, commercial forms (solid and aqueous solution), physical/chemical properties, impurity limits, sampling and analytical test procedures, and guidance on labelling, transport and storage. It clarifies that national regulations and approvals remain applicable; conformity with EN 1199:2005 does not by itself guarantee legal acceptance in every Member State.
Key topics and technical requirements
- Identification and composition
- Chemical formula: Na2HPO4; relative molecular mass 142.0; CAS 7558-79-4.
- Commercial forms: white powder/granules or clear solutions.
- Physical properties
- Solubility ≈ 80 g/L at 25 °C; bulk density 550–1 000 g/dm3; 50 g/L solution density ≈ 1.045 g/mL; pH of 1% solution ≈ 9.0–9.2.
- Purity criteria and composition (dry mass basis)
- Phosphate (expressed as P2O5): (50 ± 1.0) %
- Sodium (expressed as Na2O): (43 ± 0.5) %
- Impurity limits (mg/kg dry product)
- Sulfate (SO4 2–): max 500
- Fluoride (F–): max 10
- Trace element limits (mg/kg)
- Antimony, Arsenic, Cadmium, Selenium: max 3
- Chromium, Lead, Nickel: max 10
- Cyanide: max 5
- Mercury: max 1
- Test methods and sampling
- Labelling, transport and storage
- Provides requirements and recommendations for safe handling, labelling and storage appropriate to water treatment chemicals.
Applications and users
- Intended for water utilities, municipal and industrial water treatment operators, chemical manufacturers and suppliers, analytical laboratories, regulatory bodies and consultants specifying or approving chemicals for drinking water treatment.
- Typical uses: corrosion control, sequestration and pH buffering in potable water systems where disodium hydrogen orthophosphate is applied as part of treatment dosing.
Related standards and regulatory notes
- EN 1199:2005 cross-references multiple ISO/CEN methods for elemental and impurity analysis. Users should also check relevant national regulations and drinking-water directives before use, since EN conformity does not replace legal approvals.