You need two gallons of water per person per day. This is actually higher than is strictly necessary but you will be very unhappy if you ever have to restrict yourself to this amount. I store enough water for everyone in my household for a bit more than two weeks. Get a WaterBOB because it is so inexpensive and easy. Once you have those basic levels you then have to have a means to filter more water for your use. I highly recommend getting at least two Sawyer Squeeze and consider getting something like a Big Berkey. Find a way of collecting rainwater if you can. If you live in a desert, unfortunately you're going to have to find a way to store a lot of water.
It’s impossible to carry all the food you will need for a week unless you’re eating very high density proteins like nuts. Nuts and dried meat are two of the easiest off-the-cuff meals. Canned food has a lot of water that is wasted during the cooking process. Stay away from heavily flavored or salted nuts. The amount of salt present in the unsalted nut mixes is still sufficient enough to replace electrolytes.