The cancer-causing radioactive isotopes will be 100% removed first.
The remaining tritium will be in concentrations lower than the standard for human drinking water, and then of course that will be
radically-diluted in the ocean.
On top of this, guess what? Tritium has always existed in the ocean anyway and has never been a problem.
The fuss we're hearing about is IMHO brought about by Korea, China and maybe some others' objecting without even sending scientists over to check the levels for themselves, something a bunch of big-hitting countries such as the US and UK have done. All organisations, countries who bothered to test and the international watchdog itself have confirmed that the levels are a nothing burger.
It's obvious there are axes to grind and political agendas to fulfil. It's all about optics these days, ya know?