Purification devices set up at the site are able to remove most of the radioactive materials from this water, except for tritium, a radioactive isotope of hydrogen that can’t be removed for “technical reasons.” Consequently, tritium-contaminated water continues to increase, despite the fact that there’s increasingly no where to put it.
Looks like it's the other way around, the actual water is radioactive via tritium sitting in the place of typical hydrogen atoms in H2O.
Electrolysis. That would break the bonds into oxygen and everything else. You'd end up with a slurry of salt, crud, and tritium. But tritium only releases beta particles anyway. It's half life is a little over a decade. This isn't a serious problem and it won't be a problem for very long, comparatively speaking.
What, they can't boil it? It's not the water that's radioactive. It's the sediment in the water.