Checked TEPCO’s press page, they released their latest analysis of the pool water. Even accounting for two half-lives of I-131, the activity is considerably less today than it was 16 days ago. It’s not a huge difference, I’m just curious as to why.
If filtering, one must be careful about dose rates building up around the filters.
World's Only Rational Man 
If they are filtering ( either by a plain spun filter or ion exchange, or a combination of both) then they will reduce the contaminants in the water, and could possibly use it as coolant again.
If they are doing a straight cascade of filters before release then they will reduce volume of low level waste considerably, they just need to add cascades until the reading is at local background, which probably will leave water that is classifiable as having the same makeup as bottled water.
Will result in a pile of contaminated filters to be stored until they decay, but if they simply keep moving the filters up the cascade as the first becomes blocked, and put the newest at the end, you will do a lot of capture for a minimal amount of media. The pump may be uncleanable at the end, from material driven into the volute and impeller, so a cheap pool pump or pond pump probably would be best, and a few sand filters filled with ion exchange resin in series at the outlet will probably work as a quick and dirty filter. All available off the shelf, and can be thrown together quickly.
There’s a standard filtering and cleaning system, but it’s probably a safe bet that it’s not working.
The problem (from an RCT’s point of view) with running in a new system is that you’re concentrating that massive activity. Unless you also rig up some serious shielding, you’d better be able to do everything with robots. At this point, as long as the activity isn’t escaping I guess it doesn’t matter.
You could slap that lot on a wooden pallet, and use a flexible hose for inlet with a strainer. Robots could push it into place, and a remote operator can drop the hose in the water, with a long agri pipe leading off to a holding tank. When full or pond is empty, you drop the whole lot in a skip and move to next one with a new one. At the end the volume is more concentrated, and much easier to encase in a concrete block.
Its my preference that you not list my name on this query unless it is necessary (supposed to be working!). I wonder if you could point me to a reliable source for understanding internal dose measurement? I noted that TEPCO had a release on internal dose recently and I imagine someone waving a meter over the body like the tricorder on StarTrek. I just read this article re the two Fukushima workers who stepped in radioactive water and hung around after dosimeters went off have higher levels of exposure when internal dose is factored in: http://smartinvestor.in/market/story-71378-storydet-Two_workers_exposed_to_high_radiation_at_Fukushima.htm
I putting up a post on it now, thanks for the link!