We require clean water to live. You can last about 3 weeks without food but only about 3 days without water. A hurricane Katrina responder told me that lack of drinkable water was one of the worst aspects of the disaster. Drinking contaminated water can lead to sickness or death.
Water emergencies include: (1) lack of water which requires storing water, and (2) contaminated water which requires filtering. In early 2021 a bad winter storm caused the water system in Mississippi to fail. Residents required bottled water. Stored water would have made this bad situation much more bearable. Contaminated water can be filtered or purified.
In an emergency you need a way to filter and store clean, drinkable water. FEMA recommends a 3-day supply of water but I recommend storing two weeks of water per person. Budget one gallon of water per day per person. Water filtration and storage is easy and affordable with some BPA-free containers and a quality water filter.
Every vehicle and hiking kit should include a basic water filter and stored water. Every home should have a more advanced 0.02 micron water filter. You should always have a way of carrying water. A hiking kit includes a hydration pack, a Bugout Bag can contain a water bladder, and a heavy dry bag can be used for waterproofing items also carrying water.