Overview
ISO 13164-4:2023 - Water quality - Radon-222 - Part 4 specifies a test method using two‑phase liquid scintillation counting for determining radon-222 (222Rn) activity concentration in non‑saline waters. The standard describes sampling options, reagents and apparatus, extraction and counting procedures, calibration, and data reporting. It is intended for measurements typically above 0.5 Bq·L−1 (typical detection limit for a 10 ml test sample with 1 h counting). Annex A provides example counting parameters and validation data to meet drinking‑water monitoring needs.
Key technical topics and requirements
- Scope and applicability: Designed for non‑saline waters; laboratories must verify method validity for untested matrices.
- Sampling: Guidance on sampling approaches and on‑site vs. off‑site source preparation to control radon loss.
- Two‑phase liquid scintillation counting: Extraction of 222Rn into a scintillation cocktail and measurement using two‑phase counting techniques.
- Calibration and efficiency: Procedures for preparing calibration sources, determining counting efficiency, and optimizing counting conditions.
- Quality assurance / quality control (QA/QC): Requirements for blanks, instrument verification, contamination control, interference checks, analyst competency, and method verification.
- Data treatment: Calculation of count rates, activity concentration, combined uncertainty, decision threshold, detection limit and probabilistic coverage intervals.
- Reporting: Required elements for the test report (sample ID, method details, uncertainties, limits, etc.).
- Modification allowance: Sample volume and counting time may be adjusted to meet target detection limits or national guidance.
Practical applications and users
ISO 13164-4:2023 is practical for organizations that need reliable radon‑222 measurement in water, including:
- Environmental testing laboratories and accredited testing bodies (ISO/IEC 17025 laboratories)
- Drinking water utilities and public health agencies monitoring compliance with guidance levels (e.g., WHO guidance ~1 Bq·L−1)
- Regulators setting or enforcing water quality standards
- Research institutions studying groundwater radon variability and geogenic sources
- Industries managing naturally occurring radioactive materials (mining, oil & gas) and wastewater monitoring
Benefits include a standardized, validated approach for radon measurement, improved comparability of results, and documented QA/QC practices to support accreditation and regulatory compliance.
Related standards
Keywords: ISO 13164-4:2023, radon-222, water quality, two‑phase liquid scintillation counting, radon measurement, drinking water monitoring, detection limit, non‑saline waters.
Open preview (PDF)Water quality — Radon-222 — Part 4: Test method using two-phase liquid scintillation counting