A water container and a water supply are different things. Empty containers do not include drinking water.
The UK Be Ready checklist uses three litres of drinking water per person per day as a starting point, for three days. Allow extra for other uses and pets. Follow relevant storage guidance and the container manufacturer's instructions.
Choose food your household normally eats that keeps without refrigeration and does not need cooking. Check dietary needs, and include a manual opener for tins without ring pulls.
Follow current official guidance and individual clinical advice where relevant.