Tritium and deuterium are stored in small glass beads.
They are filtered out of water.
Tritium and deuterium are chemically same as hydrogen and are bonded with the oxygen to form water. All will pass through the same filter.
Centrifuges can separate out the heavier atoms. This is feasible with deuterium as it is about 0.03 percent but tritium is only about 10-15% of the hydrogen.
Electrolysis would then be required to separate the hydrogen isotopes from the oxygen.