I am looking for information on if the peanut and vegetable oils that come in plastic jugs that have a handle on them can be reused as water storage containers. If they can what would need to be done to make sure they oil/grease was all out of the container to be able to use it to store water in it.
Sure. Water storage containers basically just need to be made of food-safe material and not have anything on them that would make the water taste weird, and since these just held oil there wouldn’t be anything to dissolve into the water. Put a few drops of dish soap in, fill halfway with water, cap and shake until sudsy, and drain and rinse a few times (until no longer sudsy) and you’ll be good to go.
Depending on the type of plastic (thus the point at which it softens, temperature-wise) warm or hot or boiling water and baking soda (sodium bicarbonate, a base, which will turn the oil residue into soap) works for me. Fill it up and give it a nice long soak, with a tablespoon or two (15-30 ml) of baking soda in each jug.
A specific example is that it has worked to get the taste of kalamata olives out of plastic containers that retained their scent after several normal washings.
I have not had to resort to washing soda (sodium carbonate, or baked sodium bicarbonate) or lye to get results.