When sprouting for myself, I've never bleached the seeds.
That said, I have been sprouting seeds (wheat/oats/BOSS) for my
rabbits and
chickens. The standard process is to add a "splash" of bleach to the initial soak
water. This is to address mold, not E.coli. I just can't bring myself to use bleach. Whether because I don't add the bleach or other environmental factors, I struggle with this sprouting process to the point that I've decided just this morning that the remaining grain (100lbs worth) will be fermented for the
chickens and ducks but not fed to the rabbits (they can't eat fermented foods). I'm just done with trying to keep the sprouts mold free/ferment free. So, the rabbits will get their daily ration of forage and pellets rather than forage/sprouts and occasional pellets.
I say all that to say this: I don't think it is necessary to use bleach to prevent E.coli...mold would be a more likely problem. Oh, and DON'T try to replace the bleach with vinegar...the vinegar will prevent the seeds from sprouting at all. Don't ask me how I know this....