According to METI[1] on summer 2019, there where 1.1*10^9 L of contaminated water with radiation of "≦a few hundred Bq/L". Assuming 200, we get 0.22 TBq of radiation in total.
In comparison, based on reports of US Nuclear regulatory Comission, US reactors in 2003 dumped more than 1.50 PBq of tritium[2].
To me, the "less then few hundred Bq/L" seems a bit low, but I could not find any other sources.
Edit:
This [3] reports that total tritium is about 860 TBq, so, apparently, I just don't understand correctly the "few hundred Bq/L" part. This would translate to 716667 Bq/L or ~ 12 times the Japans drinkable water limit.