Preparing your water supply should be one of the first things to get together. Our local water supply was down for 5 days during Katrina. People were lined up for over an hour to receive two gallons of water. You should be prepared for one gallon of water per person, per day. However, for cooking and cleaning purposes, I would suggest two gallons per person per day. A two week supply on hand at all times would be best. More if you have to room.
Milk jugs are a great way to store water. Clean them thoroughly first. Start saving them now. Once filled store them in a cool dark place. Rotate them every six months for safety using the old water for flushing the toilet.
Remember, if it is extremely hot outside you will need to drink more water than normal.
You can invest in a rain barrel. I have found them as cheap as $65. However, if you live in a dry area, I would not count on this for your main water supply. The water from them can be used for washing and flushing toilets.
You can buy rain barrels at many stores. Our local Tractor Supply had them on sale last week.
Remember Prepare Now.