Consider these things.
1. Storage: <1 month
A: Plastic bottles. Plastic breaks down etc, health risks are small compared to dehydration, Store 10 days of water in plastic for portability and convinience. I'd suggest all in 1/2 liter bottles because as previously stated we don't drink this long term this is just for convinience and portability, and I know you can't carry more than 3-4 gallons per person in a pack and it wouldn't be practical to carry more than 20 gal per person even in a truck.
B: Storage tank If you really wanted to store some water, get a few 30 to 100 gallon cold water storage tanks (the kind we with wells use) put them into your home line. this means you have 30 gallons minimum of water stored on site at all times, that also automatically is refreshed with fresh clean water that isn't contaminated. Keep in mind your hot water tank also does this. This assumes the city water you already have is ok and not poisoned. Now you don't have to rotate your plastic containers. I'd recommend having 30 days, so for a family of 4 you would need to store 120 gallons, you can get 2 60 gallon tanks, but I priced the 36 gallon tanks at $130ish, $3 per gallon may seem steep, but you don't have to rotate it, worry about it getting old, worry about overusing your stash that you are rotating, or think about it and you have about 30 lbs of steel scrap when you are done using it
2. medium term water supply treatment: Its not practical for any of us to think we can store much more than a months worth of water, nor is it economical so a longer term solution must be found.
A: Iodine (I have a few bottles of iodine tabs bc they are convinient) NOt a long term solution you don't want to ingest that much iodine, also it does not filter out heavy metals etc. Great for moving around or camping.
B: Filter: I have a hand filter pump that I use camping which I keep about a dozen extra filters for, also a good idea to have one because it is extremely portable
C: Personally I'd rather have 20 gallons of bleach stored than the 80000 gallons of water it could treat (at 1 tsp per gallon you can treat 3840 gallons per gallon of bleach, this is for cloudy water, not relatively clean water where you would use half as much). If you live in an arid area where there are literally no freshwater streams within 10 miles of you you might have a different opinion. Note Streams are better than ponds/lakes because of less stagnation. if it is in a stream you can be reasonably assured it has been naturally purified by the water table or by the giant still called the rainclouds in the last month so it can't be that bad...
http://www.ci.oswego.or.us/wtp/EmergencyWaterTmt.htmThe "forever" solution:
I have all the stuff on hand to convert my pressure cooker into a basic still. I could easily distil 50 gal of water a day with firewood assuming all I wanted to do all day was feed the fire, feed the still fresh water and chop wood etc. but in an emergency situation I can see myself stilling 50 gal on monday and doing other tasks th remainder of the week. This is my "forever" solution. It is also useful for "other" distillation projects which could come in handy during a collapse.