InfoTracer: Groundwater 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 whereby an artificial marker, which is still detectable at very high dilution, is injected into the water, enabling its underground pathway to be followed.

Objectives of InfoTracer

Coordination of these tests is necessary primarily because artificial substances, though they may be toxicologically harmless, are deliberately released into the hydrologic cycle. The purpose of InfoTracer is to collect detailed information on the injections performed and to minimise their impact by means of:

  • Preventing interference between tracer tests conducted in the same region;
  • Notifying the cantonal environmental authorities and coordinating with the hydrogeological professionals carrying out tracer tests;
  • Archiving of the most important metadata of the reported tracer tests for subsequent access;
  • Providing information on the appropriate use of tracers in groundwater.

The system is free and operates by active voluntary contributions from all the involved persons.

Tracer test announcement

Those responsible for carrying out tracer tests (private consultancies, research institutes etc.) are asked to announce their tests promptly (at least one week in advance) to InfoTracer. A tracer test should be reported using the form below and sent to

Reporting form (only available in German, French and Italian)

The InfoTracer database compares the information provided (date, injection point and setting, tracer used, institution responsible) with the work already on the database. The cantonal environment authority is informed about the announced tracer test and InfoTracer concurrently sends a list of all past tracer tests recorded for that region to the responsible person. Tracer test results, however, are not archived.

Tracer test coordination by InfoTracer
Tracer test coordination by InfoTracer

Tracer tests in Switzerland

Since its establishment in 1984 – initiated jointly with the Swiss Society of Hydrogeology (SSH) – more than 9000 tracer tests have been reported and recorded in the InfoTracer database. A large number of archived tests has been performed in karst aquifers as well as unconsolidated aquifers in the river valleys. A quarter of the approx. 300 tracer tests reported each year involve direct injection into the groundwater. The majority of tracers are injected into the unsaturated zone or into surface waters which potentially interact with groundwater.

Tracer tests recorded by InfoTracer:  

Employment of tracers

InfoTracer also acts as an information centre regarding appropriate use of tracers in hydrogeology.
The practical guidelines on the application of artificial tracers in hydrogeology are designed to meet the requirements for planning, execution and evaluation of tracer tests. The choice of marker and the quantity injected depend on the subject of the study and the test performance. Tracer tests carried out as recommended in the guidelines can be assumed inoffensive.

Further information

Last modification 01.02.2023

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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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