The company I work for has a few 55 gallon dark blue plastic barrels that were used to hold windshield washer fluid. My question is will they be safe once bleached and cleaned to store and drink water out of.
I don't know if I would store water in them. I'd have to clean them out real good and let the sun bleach them for awhile to see if there was a lasting smell. If there's a smell your water is going to taste like that smell. It's like storing foods in pickle buckets, if you aren't careful, everything tastes like pickles.
you will have to power wash them real good. with a very high pressure flow of water. then bleach it, vinegar also helps too, from what i heard, and power wash it some more. even if it seems clean enough, i would rather use it to flush the toilet, or for small baths/showers, or sponge baths. maybe clean dishes. water for plants. some other uses other than drinking water.
I have used laundry detergent buckets, with tight fitting lids for my flour and sugar storage for years now. It was a trial and error at first. My flour smelled rancid (like detergent) so I ended up bleaching and sun drying for days, but haven't had problems since.