[en] Sources of tritium, both natural and artificial, are covered, the latter including tritium in nuclear reactors. Tritium occurence in the atmosphere, ocean surfaces, ground water, surface water and solar winds is discussed. Detection using liquid scintillation counters is assessed. Tritium as an environmental problem and radiation hazards of tritium in the human body are considered. The experimental procedures for determining the tritium content of the environment are detailed. Experiments included the determination of tritiated water in air, tritium in sea water, in reactor hall air and in reactor dump tank water. The errors are evaluated, results presented and discussed. (U.K.)