I used about a cup or two on my 20 gallon tank, but I was still using the water with bleach added for hand washing, dishes etc. You may want to go a little stronger if you just plan to flush it out. Maybe 8 cups or so. You don't want to mix it too strong since you have to stay there I assume.
After you add the bleach run all your faucets so that there is bleach solution in the lines and let it sit overnight, then continue flushing out all the lines. Then refill your tanks with fresh water and see if the problem is gone if not repeat with stronger bleach solution. That should do the trick.
I read somewhere, I believe in this forum about a guy that added half a bottle of white wine to his water tank, but I have never tried that myself.