The examination helps clarify a dispute concerning contamination of a water body, wastewater discharge or changes in water quality. The test report itself gives the parameters of a particular sample; the source of contamination and its connection with an event require separate substantiation.

Subject of examination

  • A river, stream, pond or other water body
  • Wastewater, an outlet and a suspected source of impact
  • Sampling documents, laboratory test reports and changes in parameters over time

Sample questions for the expert

  • Which changes in water composition and properties are confirmed by the examinations submitted?
  • Are the sampling conditions, locations and timing sufficient to answer the questions posed?
  • Is there data linking the identified changes to a particular discharge or other impact?
  • What source data is needed to assess the extent of the impact and restoration measures?

The final questions are formulated according to the objects and circumstances of the particular task.

What to prepare

  • A plan of the water body, outlet and sampling locations
  • Sampling records stating the date, time, conditions and sample transfer information
  • Complete laboratory test reports and a description of the methods and parameters examined
  • Information on precipitation, the source's operating pattern, background measurements and earlier measurements

How the examination is conducted

First, the object and period of the dispute are defined. Sampling locations, background conditions, properties of the suspected source and examination results are then compared. If source data is insufficient, the conclusions state the limitations and the additional materials needed.

Scope and limitations

Drinking water analysis, wastewater examination and assessment of a water body's environmental condition are different tasks. The parameters and need for a laboratory are agreed according to the object. A single result without sampling information cannot automatically identify the responsible party or establish the condition of the entire water body.

What the deliverable records

The opinion describes confirmed changes, the suitability of source data, a possible causal link and the limits of the conclusions reached. Where necessary, restoration measures are substantiated separately.

How water results from different locations and dates are compared

To assess a suspected impact, it is useful to compile a separate data entry for each sample: identifier, coordinates or a clear description of the location, sampling date and time, condition of the object and reference to the test report. This shows whether the results relate to the same event and whether they can be compared.

The name of a water body does not replace the examination location. Water near a suspected outlet, upstream or downstream, in a stagnant area or after mixing may reflect different conditions. For wastewater, information on the operating pattern of the source and discharge is also important. Weather conditions, precipitation, system cleaning and other changes are recorded as circumstances that must be considered in interpretation.

What to check in the set of test reports

  • Whether sample identifiers match in the sampling record and laboratory document.
  • Whether the measured parameters, units and methods used are comparable.
  • Whether storage conditions, delivery times and the condition of the sample on acceptance are known.
  • Whether the purpose of the comparison location and its suitability for assessing the proposed explanation are explained.

A change in a parameter after an event and identification of the contamination source are different stages of a conclusion. To assess causation, results are compared with the locations of sources, their operating times and possible alternative inputs. One sample may confirm the condition of water at a particular place and time, but does not by itself describe the entire water body over a long period.