I carry mine in 5 gallon plastic jerry cans that I bought from West Marine.

Whatever that guy is putting in his water, I sure wouldn't drink it! Water does not "sour." Not, that is, unless you've already got something growing in your container when you put the water in! If the container is clean the water will last for months without problem.

I normally use about a gallon a day.

donmillion is absolutely correct about the water and how much is used everyday. I have packed in many a "dry camp" and water does not sour if it is clean to begin with. If in doubt, add a tablespoon of chlorox to every five gallons.

They make big 10+ gal water jugs with dispenser and screw top and insulation if your going to be using a vehicle or pack horse into camp. Probably not a good idea if you are going to be hiking in though since the weight can add up, plus they are cumbersome....

About water souring. Some years ago in the fall my Dad left a one gallon water jug with water in it sealed up in our basement accidently. Forgot to empty it after a trip.

The next summer when we were heading out for a trip, I grabbed the jug and noticed it was full. Upon opening I found some small strange, oddly colored plant life had grown in the jug over the previous 9 months or so. Not much, but it could be seen with the naked eye.

Water doesn't sour, like the others have said; however if the water does have some biota in it and is left for a long time, you might be suprised at what grows. I certainly was!

As a practical matter you aren't going to have a problem with tap water for five days. If your concerned about it, take Swollen Tongue's suggestion or perhaps some water purfication tablets....