Short-Term (1-2 years) - canned goods and items from the supermarket. Ammo for my hand-guns and rifles, paper goods, a water conservation system (2 dozen blue barrels and a rain-catcher system),learning how to can and dehydrate anything that will last and vacuum sealing or dry-canning that which I dehydrate. I also purchased some just add water meals packaged for convenience. I'm thinking that these meals will get me through the first few weeks/months when everyone is still in a state of shock and trying to figure out the best way to do things. Non-Hybrid or heirloom garden seeds, enough for 3 years of crops) and gardening items (fertilizer, roto-tiller and materials to build the beds). All of this was accumulated over the course of a year.
Mid-Term (2-3 years)Some of the same items as in short-term storage but not so many store purchased canned items - more dried beans, rice, pasta, 3 year supply of hard red wheat, wheat grinder, etc. More dehydrated convenience foods, etc. By this time my garden should have been producing and I am putting by some of those items to add to my food storage. Again, more ammo for guns, more paper goods and freeze dried food items.
Long-Term (3-4 years) More of the same as above.
I've also included a good stash of vitamins and minerals, a still for making alcohol from composted yard and garden waste, a converter for my car so that it can run on the alcohol, I've got solar panels that can run appliances and recharge cell phones, solar oven for cooking. Several years ago I put in a dozen fruit trees, 2 avocado trees and some pecan trees. I've had several seasons of fruit and nuts from them all. I'm fortunate that at this time I'm healthy and don't take prescription medicines, but have stocked up on rubbing alcohol, hydrogen peroxide, baking soda, vinegar and and lots of other commonly used otc items. I also have a bicycle, extra tires and parts, a hand operated air pump, extra oil & filters for the car, extra water filters for my water filtration system along with bleach, bleach tablets, I have a 4 bedroom home and the ability to use a alcohol/gas run generator in order to run a/c units and refrigeration units. I have had 5/8" plexiglass panels placed over all my windows as storm windows and to make the house harder to access from the outside. I have had the glass in my storm doors replaced with lexan for the same reason.
I do something every day to try to make myself ready. Several of us in my prepper group are taking first-aid classes in the next few weeks.
What have you done to prepare for clean adequate water supply