The Reverse Osmosis (RO) system at Fukushima I Nuclear Power Plant treats water already treated by Toshiba's SARRY (cesium absorption towers) in order to remove salt before the water is fed back to the Reactor Pressure Vessels in Reactors 1, 2 and 3.
I believe the RO system was also built by Toshiba, and it started operation in August in 2011.
Looking at the photographs of the leak that TEPCO released on August 17, now we know it doesn't matter whether the pipes are Kanaflex or metal. They fail no matter what, at Fukushima I Nuke Plant. In this case, one of the metal pipe joints cracked and fell off, and the water leaked from there.
Gamma radiation was low in the leaked water but since SARRY (or for that matter, Kurion or AREVA, both of which have not been used) does not remove any beta nuclides (including strontium), beta radiation was rather high at 3 millisieverts/hour on the water.
From TEPCO's Photos and Videos Library (8/17/2012):
The system still uses Kanaflex:
How bad is the leak? About 0.2 tonnes, or 200 liters.
(Defective cast, poor workmanship (installation) either from lack of training/apprenticeship or from lack of stake in the project, or all, was the comment from a person with experience in chemical plants, when I showed these photos.)