You will need 1 gal of water per person per day. This isn’t including the water that you will need to cook or bathe with. Storing water isn’t as easy as throwing it in a jug and forgetting about it. Most people don’t realize that you should replace your water every six months. You should also use a proper container for storing your water, one that is BPA free and can prohibit uv light should be used. You never want to use a container that has had any type of toxic chemicals, no matter how many times you have cleaned it. If you don’t want to replace your water every six months you can use a water preserver that will keep your water safe for up to five years. You can also use a high quality water filter like the Berkey.