The KATRIN experiment is designed for a direct and model-independent determination of the effective electron anti-neutrino mass via a high-precision measurement of the tritium β-decay endpoint region with a sensitivity on mν of 0.2eV/c2 (90% CL). For this purpose, the 10^11 β-electrons per second from a high-luminosity windowless gaseous tritium source (WGTS) are analyzed by an electrostatic retarding spectrometer and those with energies near the endpoint of 18.6 keV are counted to obtain an integral spectrum. To keep the systematical uncertainties at the level required to reach the target sensitivity, the activity of this WGTS needs to be stable at the level of 0.1% while maintaining a throughput of 40 g/day of high purity tritium. This task is accomplished by the tritium loops system. 

In this presentation, the tritium loops system of KATRIN will be introduced and some challenges in operating a tritium containing system with high purity requirements and at low temperatures will be shown.