My wife and I have been cleaning up my son's LEGO collection since last week, we clean a small box every noon, since it's a boring task :). We just use a pair of used toothbrushes, poor LEGO parts into a big tube of water mixed with a little dish washing liquid. Then put all them into a washing bag and hang somewhere until they're dry, of course, keep them out of sunlight.

My wife and I have been cleaning up my son's LEGO collection since last week, we clean a small box every noon, since it's a boring task :). We just use a pair of used toothbrushes, pour LEGO parts into a big tub of water mixed with a little dish washing liquid. Then put all them into a washing bag and hang somewhere until they're dry, of course, keep them out of sunlight.