recommendation i give people is to always have a redundancy when you can , that get a life straw, but also get water purification tabs or drops. Get emergency water but also get water storage containers
Water i think it something people under store and its obviously the easiest to store the current the .gov recommendation is "one gallon per person per day for at least three days, for drinking and sanitation" ) i like to double that and have 2 gallons per person per day for 6 days to include room for water needed in case of medical emergency's . If you own your own home i suggest setting up a rain barrel , there are many different styles and types but something like this
even if you get hit with a storm that knockouts your power or messes up the water supply, you just collect 50 gallons of water to flush your toilets with.
For drinking water I am a big fan of these and currently have 4 but plan on doubling that by years end
they hold 7 gallons of water and are stackable and come with a spigot built in. Just this past week because of power outages in SPP network i lost power for only an hour, there was no water no neither. All I did was bring one of these up to wash dishes etc. I could have just waited for the water to come back (i knew it wasn't going to be long term ) but still gave me a chance to rotate out my water supply.