I have heard bad things about standard hdpe milk/juice containers, but they work quite well, are easily handled, and if one fails, there are many more. Milk contains fat, and needs to be washed with a hot detergent/bleach solution to remove all lipids sticking to the plastic, then a final rinse with boiling water. After that, ten drops of chorine bleach and tap water, cap it, and tape it. Will be potable for decades... centuries if left undisturbed and away from damaging sunlight.
I have found that the seams on most milk and water jugs tend to split over time. Two liter soda bottle last much longer.
“...cap it, and tape it.”
I’m all over the 10 drops and cap it, but what do you mean by “tape it?” Are you talking about those plastic heat-shrink seals? Thanks