The essential glossary: 20 technical terms every water laboratory director should know
There is a meeting that keeps happening in laboratories worldwide: the technical director, the quality manager and a software vendor representative. At some point in the conversation, someone mentions “metrological traceability” and another person nods without being entirely sure what it means. Or “measurement uncertainty” comes up and gets confused with margin of error.
In a water laboratory, technical language is not an accessory: it is the foundation on which accreditation requirements, client arguments and technology investment decisions are built. This glossary resolves the 20 most frequent conceptual doubts.
Table of contents
Block 1: Management system and accreditation
1. LIMS (Laboratory Information Management System)
Specialised software for the integral management of information in an analytical laboratory. It manages the full sample lifecycle: from reception and registration to issuance of the test report, including analysis assignment, result capture, approval workflows and traceability of every data point.
Practical context: A LIMS is distinct from an ERP (which manages business processes) and from an SDMS (which stores raw analytical data without processing it). The LIMS combines both dimensions with laboratory-specific logic.
Regulatory reference: ISO/IEC 17025:2025 incorporates for the first time specific provisions on LIMS and laboratory data management systems.
2. ISO/IEC 17025
International standard establishing the general requirements for the competence, impartiality and consistent operation of testing and calibration laboratories. It is the reference standard for laboratory accreditation worldwide. The current edition is the 2025 version (published on 27 September 2025), which replaces the 2017 edition.
Practical context: A laboratory accredited to ISO/IEC 17025 demonstrates technical competence verified by an independent third party. Its results are recognised internationally through the ILAC MRA.
Key data: More than 114,600 laboratories were accredited under the ILAC MRA as of March 2025, across 122 economies.
3. National accreditation body
The organisation designated by each country as the single national accreditation body. In Spain it is ENAC; in the UK, UKAS; in the US, A2LA, ANAB and PJLA are among the main accreditation bodies, with state drinking-water programmes often recognised through NELAP. These bodies accredit testing laboratories, calibration laboratories, inspection and certification entities. Accreditation is the formal recognition that a laboratory complies with ISO/IEC 17025.
Practical context: Since January 2025, Legionella analyses in Spain must be performed in an ENAC-accredited laboratory. Similar requirements for accredited testing exist in most jurisdictions for regulated parameters.
4. Accreditation scope
Official document from the accreditation body detailing exactly which tests, matrices and methods are accredited for a specific laboratory. A laboratory may be accredited for certain analyses and not for others: the scope determines which of its results can be issued as “accredited” reports.
Practical context: It is important to verify a laboratory’s accredited scope before contracting PFAS analyses: not all laboratories have these methods accredited.
How to verify it: Each national accreditation body offers an official scope search tool on its website (ENAC, UKAS, A2LA, etc.).
5. Accreditation audit
Periodic evaluation process carried out by the accreditation body to verify that a laboratory continues to meet the requirements of ISO/IEC 17025. It includes documentary review, real-time observation of tests and interviews with technical staff. The usual frequency is annual for surveillance visits and every four years for full reassessments.
Practical context: A LIMS greatly simplifies audit preparation: all traceability, calibration records, quality controls and approval workflows are immediately available.
6. Non-conformity
Failure to meet a requirement of ISO/IEC 17025 or of the laboratory’s own management system. It may be detected internally (internal audit) or externally (accreditation audit). Non-conformities must be documented, analysed for root cause and resolved with verifiable corrective actions.
Practical context: Transcription errors generated by manual spreadsheet management are a frequent cause of non-conformities related to data integrity.
Block 2: Metrology and analytical quality
7. Metrological traceability
Property of a measurement result whereby it can be related to a reference through a documented, unbroken chain of calibrations, each of which contributes to the measurement uncertainty. In simple terms: demonstrating that your balance or your spectrometer are calibrated against internationally recognised standards.
Practical context: Metrological traceability is not an abstract concept: it is a requirement of ISO/IEC 17025 and a sales argument for clients who need their results recognised in other countries.
Reference: EURACHEM publishes free guides on metrological traceability in analytical chemistry, particularly relevant to water and food laboratories.
8. Measurement uncertainty
Non-negative parameter characterising the dispersion of values that could reasonably be attributed to the measurand. In practice: the interval within which the true value of the measured quantity lies, with a specified confidence level. It is expressed as expanded uncertainty U = k·u, where k is the coverage factor (typically 2 for a 95% confidence level).
Practical context: ISO/IEC 17025 requires the inclusion of measurement uncertainty in test reports from accredited laboratories. A LIMS calculates it automatically and inserts it in the report.
Reference: EURACHEM/CITAC Guide CG 4: Quantifying Uncertainty in Analytical Measurement. Freely available at eurachem.org.
9. Method validation
Confirmation process, through examination and provision of objective evidence, that the particular requirements for a specific intended use are met. For an analytical method, this means determining and documenting its performance parameters: linearity, limit of detection, limit of quantification, precision (repeatability and reproducibility), trueness and selectivity.
Practical context: A laboratory cannot accredit a method it has not validated. Validation is the technical foundation of accreditation, and validation documentation is one of the most frequently reviewed elements in accreditation audits.
10. ALCOA+
Acronym for the data integrity principle in regulated laboratories:
Attributable: Each data point linked to its author.
Legible: Clear and interpretable data.
Contemporaneous: Recorded at the time of the action.
Original: Primary data preserved.
Accurate: Faithful to reality.
The + adds: Complete, Consistent, Enduring and Available.
Practical context: ALCOA+ is an implicit requirement of ISO/IEC 17025 and an explicit criterion of FDA regulations (21 CFR Part 11) and GMP. Spreadsheets cannot systematically guarantee compliance.
11. Reference standard / Certified Reference Material (CRM)
Material with properties sufficiently well established for use in the calibration of an apparatus, the evaluation of a measurement method, or the assignment of values to materials. Water laboratories use CRMs to verify that their methods produce correct results (trueness control).
Practical context: The use and traceability of CRMs must be recorded in the LIMS: lot number, date of use, result obtained versus certified value. These records are reviewed during accreditation audits.
Block 3: Water regulations 2025-2026
12. EU Directive 2020/2184 (and national transpositions)
European Directive on the quality of water intended for human consumption, transposed into national law by each member state (in Spain, through Royal Decree 3/2023 of 10 January). It replaces previous national regulations and incorporates new control parameters: PFAS, bisphenol A, somatic coliphages, chlorite, chlorate, uranium, haloacetic acids and a watch list of emerging micro-contaminants.
Key milestone: On 12 January 2026 the parametric value for the sum of 20 PFAS (0.10 µg/L) entered into force: water exceeding that limit must be declared unfit for consumption.
National reporting: the Spanish SINAC system
In Spain, accredited laboratories and drinking-water operators must upload their analytical results to SINAC (National Information System on Water for Human Consumption), managed by the Ministry of Health. The upload format is XML with a specific structure. Equivalent systems exist in other jurisdictions: DWI returns in the UK, SDWIS in the US, and similar platforms across Europe. A specialised water LIMS generates the required XML or structured file automatically, eliminating the manual process of extraction, formatting and upload.
13. PFAS (per- and polyfluoroalkyl substances)
Group of more than 4,000 synthetic compounds known as “forever chemicals” because of their extreme resistance to environmental degradation. In use since the 1940s in non-stick coatings, waterproof textiles, firefighting foams and electronics. They accumulate in the environment and in living organisms. EU Directive 2020/2184 sets parametric values of 0.10 µg/L for the sum of 20 PFAS and 0.50 µg/L for total PFAS, with stricter values in some national transpositions (0.07 µg/L for 4 priority PFAS in Spain). The US EPA has set even lower enforceable limits for individual compounds (e.g. 4 ng/L for PFOA and PFOS).
Analytical context: PFAS analysis requires LC-MS/MS technique (liquid chromatography coupled to tandem mass spectrometry) with detection limits in the ng/L range (parts per trillion). Not all laboratories can reliably perform this analysis.
14. Legionella
Bacteria of the Legionella genus, with 48 known species, responsible for Legionnaires’ disease (severe pneumonia) and Pontiac fever. Legionella pneumophila accounts for 90% of cases. It proliferates in water systems at temperatures between 25 and 45°C with low turnover: cooling towers, hot water systems, spas, jacuzzis and ornamental fountains.
Regulatory framework: In Spain, Royal Decree 487/2022 (as amended by RD 614/2024) requires since January 2025 that Legionella analyses be performed in an accredited laboratory. The official method is the UNE-EN ISO 11731 culture (10-12 days result). PCR methods (result in ~1 hour) are non-accredited alternatives that may complement control. Equivalent requirements apply under ISO 11731 across Europe and via CDC ELITE guidelines in the US.
15. Microplastics
Plastic particles smaller than 5 mm. EU Delegated Decision 2024/1441 (May 2024) establishes the methodology for their analysis in drinking water: cascade filtration of a minimum of 1,000 litres, spectroscopic techniques (µ-FTIR, µ-Raman or QCL-IR), particles from 20 µm to 5 mm and 10 priority polymers.
Regulatory status: Microplastics are included in the EU drinking water watch list. EU Directive 2024/3019 sets 2027 as the horizon for the analysis methodology in wastewater treatment plants and sewage sludge.
Block 4: LIMS technology and digitalisation
16. SaaS (Software as a Service)
Software distribution model in which the provider hosts the application in the cloud and users access it through the internet, usually via a web browser, paying a periodic subscription fee. The user does not need to install or maintain the software locally.
Practical context: A LIMS in SaaS mode eliminates the need for in-house servers, manual updates and an IT department. It is the most suitable deployment model for medium-sized laboratories that need agility and predictable costs.
17. Instrument integration
Capability of a LIMS to connect directly to the laboratory’s analytical instruments (spectrometers, chromatographs, balances, autoanalysers) and capture results automatically, without manual transcription. Integration is performed through standard communication protocols (ASTM, HL7, RS-232, TCP/IP) or through specific middleware software.
Practical context: Instrument integration is the element with the greatest impact on error reduction in a laboratory: it eliminates the main source of data integrity non-conformities.
18. Chain of custody
Continuous documented record of the possession, transfer and handling of a sample from collection to final archiving of the result. Chain of custody ensures that the sample analysed is the same one collected at the sampling point and that it has not been altered during the process.
Practical context: In a modern LIMS, the digital chain of custody starts in the field (on-site registration by the sampling technician from a mobile device) and ends with the digitally signed test report. Each transfer is recorded with date, time and responsible person.
19. API (Application Programming Interface)
Interface that allows two software applications to communicate with each other in a standardised way. In the LIMS context, APIs enable integration with client ERPs (SAP, Navision), with public administration platforms (SINAC and equivalents) and with customer portals for real-time result consultation.
Practical context: A well-documented API is an indicator of the technological maturity of a LIMS provider. Always ask about API availability before making a purchase decision: it will determine the present and future integration possibilities of your laboratory.
20. Cloud vs. on-premise
The two main deployment models for a LIMS. Cloud (typically SaaS) means the application is hosted by the provider on shared or dedicated infrastructure, with automatic updates and subscription-based pricing. On-premise means the laboratory hosts the application on its own servers, typically with a perpetual licence and internal IT management.
Practical context: The cloud model dominates new implementations in medium-sized laboratories. On-premise remains relevant in environments with strict data residency requirements or in organisations with mature IT infrastructure that prefer full control.
Key facts
▶ ISO/IEC 17025:2025 (published on 27 September 2025) is the current edition of the international standard for testing and calibration laboratories. It replaces the 2017 edition.
▶ On 12 January 2026 the parametric value for the sum of 20 PFAS in drinking water (0.10 µg/L) entered into force under EU Directive 2020/2184. Water exceeding this limit must be declared unfit for consumption.
▶ Since January 2025 in Spain, Legionella analyses by the culture method (UNE-EN ISO 11731) must be performed in an ENAC-accredited laboratory; equivalent accreditation requirements apply in most European and North American jurisdictions.
▶ EU Delegated Decision 2024/1441 establishes the methodology for microplastic analysis in drinking water: minimum 1,000 L filtration, µ-FTIR, µ-Raman or QCL-IR techniques.
▶ EURACHEM freely publishes world-reference guides on measurement uncertainty, metrological traceability and analytical method validation. Available at eurachem.org.
Want to see how Zendo LIMS implements these concepts in a real-world workflow? Request a technical demo tailored to the water and environmental sector.
Susana Martín Castaño
International Sales Consultant
With over 20 years of experience in the UK and Spain, she is a laboratory IT expert specialising in Zendo LIMS implementations. As the current head of international sales, she has optimized operations for around 40 laboratories in nearly 50 countries.
