fow water we have wells and are next to large river. The wells are deep wells and we have our own off grid power. Our inside wells have hand pump back ups designed for cold use. We bought botH bision and simple pump…. if you can afford get the simple pump it’s way more sturdy.
We use a 3 stage filter a blowdown sediment made of stain less steel a large 2 foot long 6 inch diameter water filter (blue) the cartridges can be bought on aliexpress for $15 each if bought in significant volumen. Thanks shipping is more costly. Same cartridge local is $60.
Final stage is in our main water storage tanks, we use an ozone kill with uv.
If in city getting a bathtub bladder to full just in case is a good idea but will only work if you fill before it loses pressure.
https://www.amazon.com/WaterBOB-Emergency-Container-Drinking-Hurricane/dp/B001AXLUX2
I also buy calcium hypochlorate (pool shock but WITHOUT ALGICIDE) it’s powdered chlorine. For cleaning but can be used for quick water purification at low levels. You can buy a 50 lb plastic pail for $40 now will save your life and keeps nearly forever.
For storage if you drink soda… the 1/2 gallon size are easy to clean and store water.
Things to not do.. don’t count on cheap water filters when water gets serious contamination. A small brita or some other cheap jug filters are near useless. A steri pen does work but are frail system with a good chance over time to fail. This is one area saving cash could really mess you up in a prolonged disaster.