🏞️ Sampling of water from lakes and reservoirs according to PN-ISO 5667-4 — and the winter that laboratories exclude

Physicochemistry PN-ISO 5667-4

Overview

STATUS (state of the PKN card on 23.09.2026). PN-ISO 5667-4:2017-10 is in force, publication 16-10-2017, 44 pages, technical body KT 119 (Water Quality — Basic Problems), ICS 13.060.10 and 13.060.45, "Implements: ISO 5667-4:2016 [IDT]", "Replaces: PN-ISO 5667-4:2003 — Polish version". The card contains no withdrawal note and no "Replaced by" row.

THE STANDARD IS IN FORCE IN THE POLISH COLLECTION ONLY IN ENGLISH. In the catalogue of the PKN shop, under the number PN-ISO 5667-4:2017-10 there is only the card of the ENGLISH version; the POLISH version remained with the 2003 edition, which has been replaced. This is the same arrangement as with the sister part 11 (groundwater): the older edition in Polish, the one in force in English. For a laboratory this means that a working translation used in the procedure is the responsibility of the laboratory, not of PKN. WE DID NOT READ THE CARD OF THE 2003 EDITION — the PKN service stopped responding during the work; we do not give its withdrawal date, because we did not see it.

WHAT THE STANDARD COVERS AND WHAT IT DOES NOT — FROM ITS OWN CLAUSE 1. The scope covers the design of sampling programmes, techniques, and the handling and preservation of samples, for water from natural lakes and man-made reservoirs, DURING OPEN-WATER AND ICE-COVERED CONDITIONS. The standard applies to lakes with and without aquatic vegetation. And the sentence that decides the limit of application: "Guidance on sampling for microbiological examination is not included" — the standard does NOT CONTAIN guidance on sampling for MICROBIOLOGICAL examination. This agrees with what stands in the scopes: next to this standard the methodology is "Pobieranie próbek do badań chemicznych i fizycznych" [sampling for chemical and physical tests], never a microbiological one.

EXCLUSIONS OF CLAUSES — MEASUREMENT ON THE ACCREDITATION SCOPES (reading of 23.09.2026). The standard is cited by 49 entries at 47 laboratories — when matching by the BEGINNING of the notation, i.e. the way the "Laboratories" tab searches for this entry, the result is 44 entries at 43 laboratories; the difference is made by notations with a spaced-out or separated prefix. 19 entries at 18 laboratories do so WITH clauses EXCLUDED. Distribution of the excluded clauses: • clause 15 — 14 times, • clause 13 — 12 times, • clause 14 — 9 times, • clause 16 — 4 times, • clause 6.2.3 — 3 times. WHAT THESE CLAUSES ARE (from the table of contents of the ISO 5667-4:2016 edition, i.e. the document implemented by this standard): 13 — sampling with closed samplers; 14 — sampling for the determination of volatile parameters; 15 — sampling through ice cover; 16 — severe frost conditions; 6.2.3 — vertical distribution of sampling points. THE CONCLUSION THAT FOLLOWS DIRECTLY: the exclusions are not scattered across the standard, but concentrated in ONE part of it. Three of the four most frequently excluded clauses concern winter sampling and closed samplers. A laboratory excluding clauses 15 and 16 declares that it does not take samples from under the ice — while the standard covers such sampling explicitly, in its scope.

HOW EASY IT IS TO COUNT THESE EXCLUSIONS WRONGLY — AND WHY WE GIVE THE METHOD. A notation in a scope looks, for example, like this: "PN-ISO 5667-4:2017-10 z wyłączeniem p.15 PN-EN ISO 5667-6:2016-12 z wyłączeniem p.7.6". Extracting all numbers from such a notation puts "clause 10" and "clause 4" at the top of the list, which nobody excludes: the first is the ending of the designation ":2017-10", the second is the PART number of the standard. In addition, clauses 7.3 and 7.6 belong to part 6, standing in the same field. The numbers above were counted differently: the fragment of the notation concerning THIS standard cut off at the next "PN", and the numbers taken only AFTER the word of exclusion — in both forms, the full one ("z wyłączeniem") and the abbreviated one ("z wył.") [both: excluding].

WITH SAMPLING FROM LAKES, A MEASUREMENT ALSO STANDS IN THE SCOPES — AND THE STANDARD ITSELF PROVIDES FOR IT. In 16 entries, next to the sampling methodology there is "Temperatura pobranej próbki wody" [temperature of the water sample taken] or just "Temperatura" [temperature], and in 16 entries PN-77/C-04584 (temperature measurement) stands in the same field of reference documents. The declared ranges differ between laboratories: (0.0 – 50.0) °C, (3.0 – 50) °C, (0 – 35) °C, (0.0 – 30.0) °C, (1.0 – 25.0) °C, (1.0 – 35.0) °C, and in one case (1.0 – 85.0) °C. This is not gluing a foreign activity onto a sampling standard: clause 5 lists among the elements of the programme "measurements made at the sampling point, e.g. temperature, dissolved oxygen, pH, turbidity, conductivity", and clause 9 puts in situ measurement IN FIRST PLACE in the order of preference — before filling the containers.

THE ORDER OF PROCEDURE IN CLAUSE 9 IS CONTENT, NOT EDITORIAL ORDER. The standard requires first recording the UTM coordinates and the water depth (usually the deepest point of the lake), and then choosing the method so as to REDUCE THE NUMBER OF TRANSFERS of the sample between the equipment and the container. The order of preference: in situ measurement → filling the container directly, without a sampler → indirect filling from the sampler straight into the containers → collection with a sampler and later distribution into containers. Each successive variant means one more transfer and one more opportunity to contaminate the sample.

31 FORMS OF NOTATION FOR 49 ENTRIES. The most frequent is "PN-ISO 5667-4:2017-10" (16 entries), followed by notations with an exclusion attached. Among the rare ones are "P N - ISO 5667-4:2017-10" with a spaced-out prefix and "PN-ISO 5667-4 :2017-10" with a space before the colon. For comparison: with PN-C-04605-02 (aluminium in water) there are three forms for 26 entries. The spread of notation is not a feature of the database of scopes, but a feature of a particular standard — it grows where a list of excluded clauses is attached to the number.

MATRICES IN THE SCOPES: "Woda" [water] (34 entries), "Woda powierzchniowa" [surface water] (8), "Wody powierzchniowe" [surface waters] (2), in individual cases with the addition "(zbiorniki zaporowe)" [(reservoirs)]. Some laboratories add "Woda do spożycia przez ludzi" [water intended for human consumption] — the standard, however, concerns the reservoir, not the abstraction or the network; sampling of drinking water from a treatment works and from the network has its own part of the series (part 5).

HOW FAR THE AVAILABLE TEXT REACHES. We have a sample extract of the ISO 5667-4:2016 edition (second edition, 2016-07-01): 13 pages of the file, i.e. pages i–7 of the standard — foreword, the full TABLE OF CONTENTS with clause numbering, clauses 1–9 in full (scope, normative references, terms and definitions, equipment, design of the programme, sampling procedure up to 6.8, safety, containers, order of procedure). We DO NOT HAVE clauses 10–18 or Annexes A–E. We therefore know clauses 13–16, i.e. the most frequently excluded ones, BY TITLE from the table of contents, not by content — and we do not state what exactly they require.

NORMATIVE REFERENCES OF THE STANDARD (clause 2): ISO 5667-1 (design of programmes and techniques), ISO 5667-3 (preservation and handling of samples), ISO 5667-14 (quality control of sampling) and ISO 7027 (turbidity — the standard refers to it for the description of the Secchi disc). The document was prepared by ISO/TC 147 "Water quality", subcommittee SC 6 "Sampling (general methods)". The second edition cancels and replaces the first (ISO 5667-4:1987), which has been technically revised.

Method principle

A water sample from a lake or reservoir is taken according to a programme established BEFORE going into the field: purpose of the test, determinands, points in plan and in the vertical, frequency, equipment and method of preservation. The sampling point is usually set above the deepest point of the reservoir, and its position is recorded by coordinates and depth. The vertical distribution is established after preliminary profiling with a probe (temperature, dissolved oxygen, pH, conductivity, turbidity, chlorophyll fluorescence), because in a stratified reservoir the water quality changes with depth, most strongly in the thermocline. The sample is taken with equipment selected for the determinands — from the surface with an open sampler, from depth with a closing sampler — limiting the number of transfers between the equipment and the container.

Applications

• Sampling of water from natural lakes and man-made reservoirs for chemical and physical tests
• Monitoring of reservoirs and lakes in open-water conditions and under ice cover
• Testing of stratified reservoirs, in which the result depends on the sampling depth
• Reading an accreditation scope in which the temperature of the sample taken also stands next to sampling
• Checking whether a laboratory's scope covers winter sampling — whether the clauses on ice are excluded

Key parameters

Standard

Standard number

PN-ISO 5667-4:2017-10 (wersja ANGIELSKA; wprowadza ISO 5667-4:2016 [IDT])

Title (PL)

Jakość wody — Pobieranie próbek — Część 4: Wytyczne dotyczące pobierania próbek z jezior naturalnych i sztucznych zbiorników zaporowych

Title (EN)

Water quality — Sampling — Part 4: Guidance on sampling from lakes, natural and man-made

Step-by-step procedure

1. Establishing the programme BEFORE going into the field (clause 5)

   The standard lists the elements of the programme: purpose of the test; determinands for each point; measurements made at the sampling point (temperature, dissolved oxygen, pH, turbidity, conductivity); frequency and timing; number and position of points; equipment; quality control procedures; transport, preservation and storage; hydrodynamic and morphological features of the reservoir; local conditions (depth, vegetation, accessibility, floating or sediment layers); sampling depths; composition and quantity of water; safety.

2. Selecting and preparing the equipment (clause 4)

   Select the equipment so that it does not interact with the water — check at random the emission, absorption and adsorption of the substances determined. Clean the equipment regularly, mechanically and, where necessary, chemically, inside and out. Check the release mechanisms of the samplers periodically, and calibrate probes and electronic devices according to the manufacturer's recommendations and KEEP A RECORD of the dates and results of the checks (clause 4.3).

3. Setting the point in plan (clause 6.2.2)

   For a reservoir without marked horizontal heterogeneity, one point above the deepest point is usually sufficient. For lakes with a complex morphology — several basins, a developed shoreline — first a preliminary survey with more points, and only then the number of permanent points is established. Mark the points permanently (buoys) or locate them with a navigation device.

4. Setting the points in the vertical (clause 6.2.3)

   In a stratified reservoir the water quality changes with depth — through photosynthesis and heating from the surface, through dissolution and disturbance of sediment from the bottom, through sedimentation of suspended matter; the greatest differences occur in the thermocline. Profile with a probe, and in heterogeneous zones reduce the intervals between sampling depths. Once adopted, do not change the system of depths during the programme — data from a programme changed midway are not comparable. THIS IS A CLAUSE EXCLUDED BY THREE ENTRIES IN THE SCOPES.

5. Recording position and depth before sampling (clause 9)

   Before sampling, record the UTM coordinates and the water depth to confirm that the sample comes from the right place — usually from the deepest part of the lake.

6. In situ measurements before filling the containers (clause 9)

   Measurements made on site — dissolved oxygen, pH, water temperature, conductivity, turbidity, transparency with a Secchi disc or an optical probe — are made BEFORE taking samples for analysis. They give a picture of the stratification and make it possible to choose the depths. In stratified waters repeat the depth measurements consistently, because pH and dissolved oxygen depend on depth.

7. Choosing the way of filling — the fewer transfers, the better (clause 9)

   Order of preference: in situ measurement; filling the container directly, without a sampler or funnel; indirect filling, where the sampler fills the containers directly; collection with a sampler and later distribution into containers. Each additional transfer is an additional opportunity to contaminate the sample.

8. Containers and their preparation (clause 8)

   Select the containers for the determinands; they may require preparation in the laboratory (acid washing, cleaning, quality control procedures) or rinsing on site before use. ISO 5667-3 gives guidance, and the type and volume should be agreed with the laboratory carrying out the determinations and recorded in the procedure. With chemically prepared containers, observe precautions regarding the reagents used.

9. Safety when working on water and on ice (clause 7)

   The standard refers to ISO 5667-1, which gives precautions — including for sampling from boats and from ice-covered waters — and reminds of national and local safety regulations.

10. Entering the exclusions in the report

    If the accreditation scope covers the standard with clauses excluded, the report is to state that the test was carried out with these exclusions. With clauses 15 and 16 excluded, this means that the laboratory does not carry out sampling from under ice cover or in severe frost conditions — i.e. it does not cover a winter order.

Required equipment and apparatus

Health and safety (OHS)

• Excluding clauses 15 and 16 means that the scope does not cover sampling through ice cover or in severe frost conditions — while the standard covers such sampling explicitly, so citing it in a contract does not by itself guarantee that a winter order will be carried out
• Excluding clause 14 means that the scope does not cover sampling for the determination of volatile parameters — and this is the class of determinands for which the sampling technique decides the result
• The standard does not cover sampling for microbiological examination and says so about itself in clause 1 — citing it as the basis for taking a sample for microbiological examination is an incorrect citation
• Sampling from a lake is not the same as sampling drinking water from a treatment works and from the network — part 5 of the series is for that; the matrix "drinking water" with this standard requires checking what it concerns
• Since the 2017 edition the standard has existed in the Polish collection only in English — a working translation used in the procedure is the responsibility of the laboratory
• A sampling programme changed during its implementation gives non-comparable data — the standard states this explicitly in clause 6.2.3
• Switch off the combustion engine of the vessel at least 10 m before the sampling point; with small boats the standard indicates electric propulsion, because exhaust and oils contaminate the sample

Frequently asked questions