I used to keep store purchased gallon jugs of water, but I had problems with leakage and fragility. I now do keep cases of bottled water on hand, but rotate them regularly as the kids use up the ones in the refrigerator. Handy tip: mark each water bottle in use with the person's initials or name using a Sharpie. This way you reduce wastage, as nobody wants to drink out of the bottle that nobody knows who it belongs to.

My main store is in 5 to 8 gallon Reliance plastic containers. These are periodically emptied and cleaned, then refilled and stored. They have a variety of styles so you can find one to fit your space. They are durable, some of them very durable (I think they are called Rhino containers).