I recently scored a 325 gallon storage tank and cleaned it out with bleach to sanitize. I plan on filling it this weekend, and was curious as to how much bleach per gallon I should add to keep funk from growing in there. It will be outside, in a sheltered corner, in a shed-type structure to keep the sun out. We are on county water. Thanks!

I use 8 drops per gallon on non-municiple water.
Over time the bleach flavor disapates and you barely notice it.
Check to make sure but that's what I use.

We use 1/2 teaspoon per 5 gallons.

Just curious:  What was the tank used for before?  Are you sure it's OK for potable water?

Yep, 8 per gallon = 1 per pint.

it was used for laundry detergent. Hazard sticker on the side says little to no health hazards. I filled it twice with lotsa bleach, drained, rinsed out with a spray nozzle twice, and I cant smell anything other than faint bleach odor. the guy I got it from has been using them for years for horses and cattle water with no bad effects. Also, I checked the type of plastic its made from and that type (cant recall the acronym) is food grade, same as plastic water bottles.

Yeah, it should be just fine.  I got a bunch of 55 gallon propylene glycol anti-freeze barrels.  It's used to flush water systems in RV's and boats to winterize them.  It says you're not supposed to reuse them for drinking water, but it's completely non-toxic.  I have some 15 gallon barrels that used to have pomegranate concentrate so I'm using those for potable water, but I think as long as it hasn't contained anything that can't be flushed out it should be fine.  I'm probably going to use the 55 gallon ones for watering the garden, etc.

1/2 teaspoon per 5 gallons. According to clorox