By changing the connections TEPCO can use all three systems, or bypass one or more if there's a problem.
SARRY ("Simplified Active Water Retrieve and Recovery System") can run on its own, without Kurion or AREVA, and still be able to achieve the reduction of radioactive materials in the water to 1-millionth, or so it's claimed in the article by Asahi Shinbun. We'll see.
From TEPCO's handout for the press on August 18:
