InfoTracer: Central coordination service for tracer tests

InfoTracer is the FOEN tool to coordinate, centralise and archive information on tracer tests performed in Swiss groundwater.

Tracer testing is one of the main techniques used in applied hydrogeology; a highly diluted yet detectable substance (tracer) is added to water in order to trace the water's underground pathway and any exchange between groundwater and surface water.

InfoTracer – purpose

Tracer testing involves the deliberate introduction of artificial substances into the water cycle.  Special care must therefore be taken, even if the tracers are toxicologically harmless. The purpose of InfoTracer is to collect relevant information on all tracing activities and to minimise their impact by:

  • preventing interference between tracer tests conducted in the same region;
  • notifying the cantonal environmental authorities and coordinating with the services carrying out tracer tests;
  • archiving centrally the most important metadata of the reported tracer tests for subsequent access;
  • providing information on the correct use of tracers in groundwater and surface water.

No fee is charged for recording a tracer test in the system. InfoTracer relies on active voluntary contributions from all those involved.

Reporting tracer tests

All those responsible for carrying out a tracer test (private consultancies, research institutes, public authorities, etc.) are requested to notify InfoTracer in good time (at least one week in advance). This can be done by completing the Excel spreadsheet below and sending it to the following email address:

The InfoTracer database compares the information provided (date, injection point and setting, tracer used, service responsible) with the entries already in the database. InfoTracer informs the cantonal environment authority when a planned tracer test is recorded in the system and sends a list of all archived tracer tests for a given region to the service conducting the test. The results of tracer tests are not archived.

Tracer test coordination by InfoTracer
Tracer test coordination by InfoTracer

Tracer tests in Switzerland

Since InfoTracer was launched in 1984, around 11,000 tracer entries have been reported and recorded in the database. Many of the recorded tests were conducted in karst aquifers and in unconsolidated rock aquifers in river valleys. A quarter of the approx. 300 tracer tests reported each year involve direct injection into groundwater. The majority of tracers are injected into the unsaturated zone or into surface waters which potentially interact with groundwater.

Tracer tests archived in InfoTracer:

Map of archived tracer tests on

Use of tracers

InfoTracer also acts as an information centre for the appropriate use of tracers in hydrogeology.
Practical guidelines on the application of artificial tracers in hydrogeology provide an overview of the requirements for planning, carrying out and evaluating tracer tests. The choice of tracer and the quantity injected depend on the test object and the test set-up. Care should be taken when selecting a tracer and determining the amount used. Tracer tests should ideally be conducted in accordance with the guidelines.

Further information

Last modification 18.12.2023

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Coordination centre for groundwater tracer tests

Federal Office for the Environment FOEN

Hydrogeological Basics Section

Tel. +41 58 463 03 21

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