..... When the tank is completely filled, I add a cup of chlorine bleach, pump water through the lines until I can smell the bleach, then it's clean enough to wash dishes and vegetables.
I used to routinely test the water for bacteria, but after two years of testing and no bugs I stopped doing that. Besides, it was getting expensive. Somewhere on the Internet there is a formula for how much chlorine bleach to use per gallon when treating water. If I recall, it was about 16 drops per gallon, but I could be wrong on the formula. If you don't smell chlorine after 16 drops, add another 16 drops and wait 30 minutes. If you still don't smell chlorine, discard the water and find another source.
If you're worried about the chlorine bleach causing health problems, believe me, if you contract C-diff from contaminated foods and water it's a lot worse than anything you will experience from the chlorine bleach. Without proper medical treatment, C-diff can kill a healthy person in a matter of a few days.
Your cleanliness is admirable. Bleach works well. You could safely use much less. 1 cup of bleach for 70 gallons of water is way
I used to be in charge of a strictly controlled public water supply. We had an instrument to measure the ppm of the chlorine. Yes it depends on how dirty the water is, but you would not use water so dirty you needed that much bleach. On clean water I would use IIRC about a cup of bleach to 3000 (three thousand) gallons of water. This would keep any green growth from forming on the inner surface of translucent plastic tanks in sunshine. For known contaminated water I would double that or more, but not 40 times as much.
It is important to realize that bleach loses strength as it ages
. Sometimes I received bleach that would not show up in the measuring tubes, or just flash and disappear. This could explain not smelling the bleach. Try to buy your bleach at a busy store with a good turnover, not some dusty bottle that has been sitting around.
Even for pretty bad water you could cut your 16 drops per gallon to 8 drops per gallon.
I'm surprised your water was tested as is. I had to test regularly, and extremely minor amounts of bleach in the test water would cause the test to be voided.