Overview
EN ISO 19458:2006 (ISO 19458:2006) - "Water quality - Sampling for microbiological analysis" - is a CEN-endorsed international standard that gives guidance for planning and performing water sampling targeted at microbiological investigations. It covers design of sampling regimes, sampling procedures, and the transport, handling and storage of samples up to the start of laboratory analysis. The standard is intended to ensure representative, uncontaminated samples for reliable microbiological testing.
Key topics and requirements
- Scope and purpose: Guidance specifically focussed on microbiological sampling (living organisms in suspension) rather than chemical sampling; complements the ISO 5667 series for different water bodies.
- Sampling point selection: Choose representative sites that account for vertical, horizontal and temporal variations; avoid unstable or heterogeneous locations (dead-ends, surface films, inlet/outlet differences).
- Sampling technique and personnel: Formal training, documented competence and record-keeping for staff who take samples.
- Sample containers and volumes: Use clean, sterile bottles (glass or plastics such as polyethylene) with volumes adequate for requested analyses. Typical routine volume: 500 ml; larger volumes (up to 1 L or many litres) for pathogens (Legionella, Salmonella, viruses, protozoa) often require on-site concentration (filtration, flocculation).
- Sterilization and handling: Re-useable glass bottles should be cleaned and autoclaved or oven-sterilized; single-use plastics may be sterilized by gamma or ethylene oxide where appropriate; controls and traceability for sterilization processes are recommended.
- Inactivation of disinfectants: To accurately assess disinfected waters, an appropriate neutralizer (e.g., sodium thiosulfate) must be added at sampling to stop oxidant action - ISO 19458 gives guidance on dosing.
- Transport and storage: Guidance on temperature control, maximum holding times and preservation until analysis begins (see Annex B for recommended/acceptable storage times).
- Sampling frequency and statistics: Annex A provides methods to determine the number of samples needed to estimate mean microbial concentrations with defined confidence.
Applications and users
Who uses EN ISO 19458:2006:
- Water utilities and distribution system operators
- Environmental and public health laboratories
- Microbiologists and laboratory managers validating sampling protocols
- Regulators and consultants assessing compliance (drinking water, recreational water, pools, bottled water)
Practical uses include routine compliance sampling, outbreak investigations, disinfection efficacy studies, and surveillance for pathogens (Legionella, enteric viruses, protozoa).
Related standards
Keywords: EN ISO 19458:2006, ISO 19458, water quality, sampling for microbiological analysis, sampling procedures, sample containers, sterilization, disinfectant inactivation, transport and storage, ISO 5667.
