Murphy’s law states “what can go wrong, will go wrong and at the worst possible time”. Its important to prepare for the worst and have something in place when you may need it rather than not have it and be totally unprepared. Obviously water is a must and actually the easiest thing to have stored, it is sold in bottles and makes for easy storage and transport.
If not bottled water, then some sort of filtration system. Bottled water is a good item to have on hand and use the filtration system when you are low on bottled water so it might be good to have both. You should also have some sort of emergency radio, whether one where you can only listen to broadcasts or one where you can also reply. This would depend of your budget. As long as you have one type, it should be fine at least better than none.
Heat and a source of creating fire is next. You can get fuel gel, lighter fluid, tree shavings or just some old newspapers, it don’t much matter but importantly just do not use any treated wood to cook with. Make sure you have some way to start a fire either water proof matches, butane lighter, a flint rock, what ever you fancy as long as they will work. Lastly you should have some spare clothes, shoes, coats, and some sort of portable shelter and a way to either carry or transport the supplies if needed to move for better protection and possibly aware from the disaster area if you are at threat.
Emergency situations happen every day.
