Water:
In an ideal situation, you should store at least two weeks worth of water for every person in your family. Generally water is figured at 7 gallons of water per person, per week, and that's only drinking water. So for a five person family, you should try to store, purify and rotate 70 gallons of water. This is a lot of water though, so build up to it. I have just begun putting up water, and only have 30 or 35 gallons stored and purified, but I generally add at least another gallon a week.

Storage:
If you don't want to spend the money on USMC surplus water containers or something like that, look around your house. Soda pop bottles, plastic milk jugs, distilled water jugs, things like this are perfect for storing water and are easy to get and store. Another thing to get is the collapsible 5 gallon jugs that are sold in the sporting goods sections at stores such as Sears and Walmart. Keeps these in storage, for a time when you have no water from your public works' water system. When this happens, even though no more water is coming into your house, there is still a lot of water trapped in the water system and pipes in your house.  If this happens, turn off the main water valve into your house as soon as possible, as many times the water in the public system will become contaminated.  If you open a faucet on the upper floor of your house, you can keep from creating a vacuum in the pipes, and drain the water by opening a faucet in the basement or lower floor.  Here is where you want to use those collapsible water jugs.  The water doesn't do you much good caught in the pipes, so you should empty it into the jugs.  I would treat it with Clorox bleach at this point, as how long it is stored depends on how many people are in your family and how much water you already have stored.  There is also 20 to 85 gallons of water trapped in your water heater.  If possible, you should try to drain and flush this out several times a year, but if that's not possible(which as teenagers, most of our parents probably wouldn't let us do this), the water should be all right if properly treated.  I personally will filter, boil and then treat the water with Clorox, just to be safe.  In a situation like this, you should drink your previously stored water first, as it is more likely to be safe, yet will also likely be safe for a shorter amount of time.
 

Purification:
Purify with clorox (2drops per quart of water or 8 drops per gallon) and rotate the water every three months. Clorox is very cheap, and if you can afford it, get Aerobic 7 water purification drops. When used in water, the water can be stored for up to 5 years without rotation. I also rotate my Clorox every two months and get new bottles.  If you are preparing for a whole family, buy several bottles each time, as they are cheap anyways(about $1.05 in my area), and are good for so manyh other things.  I always use my newest Clorox for purification, but I also keep the older Clorox for about six months or more, to use for decontaminating things, such as a very mild chlorine rinse as part of the dishwashing process(learned this on a trip to Africa).  Lastly, I would not keep Clorox in the original bottles.  These are pretty weak and have a tendency to break.  I would transfer the bleach into a stronger container.  I use one gallon milk jugs, and haven't had a problem yet.

Rotation:
Try to set a schedule for when you rotate them, and rotate all your water at once, even if you added some of it later. I rotate my water on the first day of every third month, so when March comes around, I will be rotating all my water. I rotate the Clorox on the same schedule and use one of the new bottles for the new water.
 

Food:
 1- Offer to shop for your Mom so you can pick up 1 or 2 items for your
 storage.  (ask first)

 2- Items to get:  Small cans of meat and fish (abt. $1.25), chicken and
 beef boulion granules (Granules are easier to measure), the smallest
 pasta you can find (can be stored more densely), dried fruit, canned or
 jarred nuts, 1 pound bags of beans and pulses (pulses= yellow & green
 peas, lentils), pearled barley, Rice-a-Roni, Canning salt (has no
 additives and will cake.  Put a few grains of plain rice into it to
 absorb the moisture), curing salt, canned instant potato granules, boxes
 of scalloped or au gratin potatos, grits, canned bacon bits, dried
 onions and garlic, sugar, honey, peanut butter, jam, small cans of
 crisco.

 3- grow your own herbs and dry them yourself.  They can be grown in
 flower pots in a sunny window.  cut them a leaf at a time and lay them
 on a paper towl out of the light until they are dry.  Put them in jars.
 They will keep for 1 year.  When they start to lose their color, replace
 them.

 4- Have your Mom buy spaghetti sauce in the canning jars so you can
 reuse them for your pasta and other things.  Quart jars are perfect
 because they are uniform and can be boxed easily.  It is a good idea to
 keep your stored food in boxes anyway because the light can destroy
 vitamins.  Always err on the conservative side.

 5- get a Sharpee indelible marking pen and mark the date of everything
 you buy in the month and year that you bought it.  Get some self
 sticking lables (address lables work well) and put lables in indelible
 ink on all repackaged items.  Sharpee pens are suggested because they
 will even mark on metal and glass.  They will not smudge when damp or
 wet.  To get lables off of jars that get emptied, fill the jar with hot
 water, let it set for 5 minutes and peel off the lable.

 Make sure that you include any instructions for cooking on the lables.
 You can also include recies that appeal to you on another lable, if you
 wish.  They can be used as references.

Medical Supplies:
First thing is, buy the basics.  Bandaids, Ace bandages, neosporin, stuff like that.  Not everyone can afford to buy a field surgery kit and a supply of antibiotics to start out.  Secondly, buy in bulk whenever possible, as it will save you money, and will make it more likely that you have enough of the item to last you over a long-term survival situation, rather than just something like a week-long ice storm or tropical storms(those these can be just as bad).  Also make sure to get things such as rubbing alcohol and hydrogen peroxide, and use these in combination with some type of antibiotic ointment like neosporin on any open wounds.  In a long-term survival situation, you can NOT afford a serious infection, as without modern medical facilities, these can easily turn septic, travel throughout your body and either put you on your back for a long time or even kill you.  Even if you have antibiotics laid up, tried to stop infections early as they can still spread for a week or more after you start taking heavy antiobiotic dosages, and will lower your supplies significantly before you can deal with them.
 

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