The whole process is as follows:
Take the highly contaminated water that has been stored in the Central Waste Processing Facility (about 120,000 tonnes of it) to the water treatment system;
The water first goes through the oil separating system built by Toshiba;
The water then goes to the system by Kurion, where different types of zeolite will remove 1) the oil/technetium, 2) cesium, and 3) iodine;
Then it goes to the system by AREVA, where it gets further decontaminated; if TEPCO decides so, the AREVA system can come before Kurion;
Then finally it goes to the desalination system built by Hitachi.
After desalination, the "treated" water is stored in a series of tanks;
The treated water is fed through the 10-centimeter diameter PVC pipes to the Reactor Pressure Vvessels of the Reactors 1, 2, 3;
The water will leak through the RPVs and the Containment Vessels down to the reactor basements;
Again highly contaminated, the water then is routed from the basements of the Reactors 2 and 3 to the Central Waste Processing Facility;
Start at No.1 again.
3.5 tonnes/hour to the Reactor 1;
3.5 tonnes/hour to the Reactor 2;
9 tonnes/hour to the Reactor 3;
Total 16 tonnes/hour or 384 tonnes per day.
The water treatment system is processing more than that amount, even at the current 55% capacity (full capacity 1,200 tonnes per day). So, at least for now the highly contaminated water will not increase, and slowly decrease.
What's missing from this process is the cooling system for the circulated water. TEPCO is counting that by going through the treatment system the warm/hot water (remember the 4-sieverts/hour steam gushing out of the Reactor 1's basement) will cool off enough.