For families, I personally recommend having a 55-gallon water barrel per household. This is the most economical way to store water for the long term.
In addition to drinking, you will need water for personal needs, like hygiene, washing, first aid, cooking. Because of the demands for water, I don’t believe that the usual 3-day water supply (72 hour) is close to being enough for your family. We are suggesting to store at least one gallon per person per day for at least 2 weeks.
Our Water Barrel Package contains a 55-gallon Water Barrel, Water Preserver, Hand Pump, and Bung Wrench.