In September 2020, the IBS Center for Climate Physics (ICCP) resumed South Korea’s regular water isotope monitoring as part of the Global Network of Isotopes in Precipitation (GNIP) – an international project run since 1960 by the International Atomic Energy Agency (IAEA). The network is composed of about 1200 monitoring stations in over 100 countries and different regions. Its main goal is to obtain an isotopic view of the global hydrological cycle by monitoring hydrogen and oxygen isotopes of precipitation. This data can help constrain the inventory of water in different systems. Such information is beneficial in the context of water resource management, hydrological planning. In South Korea, there used to be two GNIP stations – one in Cheongju which ran from 1998~2016 and one in Pohang which operated from 1961-1976. Both of these stations also ran – apart from the stable water isotopes – analysis of the radioactive 3H (tritium) water isotope, – an indicator for atmospheric thermonuclear test fallout. ICCP collects rainwater samples and sends a monthly analysis of stable hydrogen (1H, 2H) and oxygen (16O,18O) isotope to the IAEA, where other researchers and organizations can download the data for further research and planning purposes.