A water test is only as reliable as the laboratory behind it
When you arrange to have your water tested, you are placing a great deal of trust in the laboratory carrying out the analysis.
You trust that the sample has been handled correctly. You trust that the equipment is accurate. You trust that the person conducting the test is properly trained and you trust that the result you receive is reliable.
But how do you know?
Choosing a laboratory should not simply be based on convenience, price or how quickly a result can be provided. Water-testing results can influence important decisions about health, hygiene, maintenance and the safe operation of a property or business.
Before you rely on a laboratory report, it is worth asking one important question:
Who is testing your water and can you trust the results?
What makes a laboratory trustworthy?
A professional water-testing laboratory should be able to demonstrate that its testing is carried out using recognised procedures, suitable equipment and appropriately trained personnel.
Important areas to consider include:
Validated testing methods: The laboratory should use methods that are appropriate for the type of water and the substance or organism being tested.
A validated method has been assessed to confirm that it is suitable for its intended purpose. This helps ensure that the laboratory is not simply producing a number, but producing a result that can be supported scientifically.
Calibrated and maintained equipment: Laboratory instruments must be regularly checked, calibrated and maintained.
Even highly sophisticated equipment can produce inaccurate results if it is not used correctly or its performance is not monitored. Calibration helps establish that measurements are accurate and traceable to recognised standards.
Competent laboratory personnel: Water testing requires more than placing a sample into a machine.
Laboratory personnel need the appropriate education, training, technical knowledge and practical experience to perform each test correctly. They must also be able to recognise when something has gone wrong and understand whether it could affect the result.
Sample control and traceability: A trustworthy result begins before the sample reaches the laboratory.
The type of sample bottle, where the sample is collected, how it is collected, the temperature at which it is stored and the time taken to deliver it can all affect the result.
The laboratory should have procedures for receiving, identifying, handling, storing and tracking samples throughout the testing process. This is sometimes referred to as the sample’s chain of custody.
Quality controls: Quality control procedures help laboratories identify contamination, equipment problems, procedural errors or unusual results.
Depending on the test, this may include the use of blanks, controls, reference materials, duplicate samples and proficiency testing. These checks provide evidence that the testing process is working as expected.
Clear and accurate reporting: A laboratory report should clearly identify:
- The sample tested
- The tests performed
- The methods used
- The results obtained
- The units of measurement
- Any relevant observations or limitations
- Whether a result falls within the laboratory’s accredited scope
If a report is unclear, you should be able to contact the laboratory and ask for an explanation.
What does ISO/IEC 17025 accreditation mean?
ISO/IEC 17025 is the international standard for testing and calibration laboratories.
Accreditation to this standard provides independent confirmation that a laboratory has demonstrated its technical competence and operates a controlled quality management system. It covers important areas including staff competence, testing methods, equipment, traceability, sample handling, quality assurance and the reporting of results.
The International Organization for Standardization explains that ISO/IEC 17025 enables laboratories to demonstrate that they operate competently and generate valid results. You can learn more on the official ISO website.
Accreditation does not mean that every possible test offered by a laboratory is automatically accredited. Accreditation applies to the specific tests and methods listed within the laboratory’s official Scope of Accreditation.
That is why it is important to ask whether the particular test you require is included within the laboratory’s accredited scope.
Accreditation is more than a certificate on the wall
An accredited laboratory must continue to demonstrate that it meets the required standard.
This includes maintaining documented procedures, monitoring staff competence, calibrating equipment, participating in appropriate quality-assurance activities and undergoing independent assessments.
Accreditation provides confidence that the laboratory has established systems designed to produce technically valid and consistent results.
It does not mean that mistakes are impossible. It means the laboratory has controls for preventing problems, identifying them and taking corrective action when necessary.
Questions to ask before choosing a water-testing laboratory
Before submitting your water sample, consider asking:
- Is the laboratory accredited to ISO/IEC 17025?
- Which organisation issued the accreditation?
- Is the test I require included within the laboratory’s current Scope of Accreditation?
- What type of sample bottle should I use?
- How and where should the sample be collected?
- Does the sample need to be kept cool?
- How quickly must it reach the laboratory?
- How long will the testing take?
- Will the laboratory help me understand the report?
A professional laboratory should welcome these questions and provide clear guidance.
Why water sampling matters
Even the most capable laboratory cannot correct a sample that was collected incorrectly.
A contaminated bottle, an unsuitable collection point or a delay in delivering the sample may affect the result. This is especially important for microbiological testing, where collection conditions and delivery times can be critical.
Always contact the laboratory before taking your sample. The laboratory can advise you about the correct container, collection procedure, storage requirements and delivery arrangements for the test you need.
Testing for homes
Homeowners may consider water testing when:
- Water develops an unusual taste, smell or appearance
- A property has a private cistern, storage tank or filtration system
- Plumbing or water-storage equipment has been repaired
- A property has been vacant for an extended period
- There are concerns about bacteria or chemical characteristics
- Routine monitoring is required for reassurance
The appropriate tests will depend on the property, the water source and the reason for testing.
Testing for businesses and facilities
Hotels, restaurants, schools, healthcare facilities, spas, gyms, apartment complexes and other commercial properties may have more complex water systems than a typical home.
Large storage tanks, low-use areas, showers, cooling systems, decorative water features and sections of pipework where water can remain stagnant may require particular attention.
A suitable testing programme should reflect the property’s water system, how the water is used and any applicable operational or regulatory requirements.
Testing can help support a wider water-management programme, but it should not replace proper system maintenance, cleaning, temperature control or risk assessment.
Know who is testing your water
A water-testing report may look simple, but every result depends on the people, equipment, methods and quality systems behind it.
Do not be afraid to ask questions. Find out whether the laboratory is accredited, confirm that the test you need is covered by its accreditation and make sure your sample is collected correctly.
Because when the result matters, the laboratory matters too.
