More Prepared offers many different types of packaged emergency water rations, water purification supplies, and storage options to meet your needs. When you are making your plan, be sure to account for a minimum of one gallon of water per person, per day.  This water will be for drinking, cooking, cleaning, and sanitation purposes.  It is advisable to have a supply that will sustain you for at least 72 hours; however, many guidelines now recommend having a supply that will last 7 to 14 days.