Water Storage

I've gone through a lot of training and learning with wilderness survival. Boy Scouts is great for that.One thing I've never known, and that I'm now quite curious about, is how to store water in a situation without modern technology for it. On a long survival trip, or in a simulated situation like on the YouTube channel Primitive Technology, how would you make a container for water?Without plastic or leather, with your main material being clay, what would you do? Would building a large, covered pot or very small clay-lined cistern be sufficient? How long would water remain drinkable after being sterilized in storage like this, that isn't airtight? http://ift.tt/2gRdWMG