A good rule of thumb is to store one gallon of water per person per day. Your plan should provide for at least three days. Remember, you’ll need more water in hot temperatures and for strenuous activities. People with special needs, such as nursing mothers, young children, and family members with illnesses, also require more water.
Store tap water in a clean, airtight container in a cool location. Do not use containers that once contained chemicals or toxic material. As a general rule, change your emergency water supply at least every six months to ensure freshness.