Fortunately tritium is a rather weak radioisotope that can be blocked by human skin. It is a carcinogen and its principle risk to humans is from ingestion. Water containing tritium is usually excreted from the human body within a month. There are other much more serious contaminants in the water tanks such as caesium-137 and strontium-90. TEPCO has deployed a filtration system intended to filter out 62 isotopes, but the system is prone to breakdowns according to Greenpeace and cannot filter out tritium. TEPCO admitted failures to reduce radioactivity to levels below regulatory limits in more than 80% of the storage tanks. Reported levels of strontium-90 were more than 100 times regulatory standards with some tanks at 20,000 times.
Environmentalist obviously do not think dumping millions of tons of radioactive water into the ocean for fish to swim in is a good idea. The Japanese public also objects to the plan. They want the government to buy more land and build more tanks until the tritium has time to decay. Ten half-lives of tritium is 123 years. TEPCO plans to remotely remove the dangerous fuel rods by 2031. Absent a near-miraculous technical development, Fukushima will continue to pose a danger to humans that live nearby for decades to come, making it the worst industrial disaster in history.