Cost of bottled water vs. tap

I often buy consumables that I wouldn't otherwise when I travel for business. I'm not suggesting I splurge on extravagances, rather these purchases are circumstantial. For example, I seldom use breath mints at home, but I always have a roll of peppermint or wintergreen BreathSavers in my pocket when I'm on the road.

Another item that only gets purchased when traveling is bottled water. I support home town companies, so my bottled water of choice is Dasani. I usually buy the 20 ounce size for $1.06 with tax.

We've all heard that bottled water is 99% profit, but what does the water itself actually cost? I decided to grab my most recent water bill to find out.

My household consists of myself, my wife, and 3 & 1 year old children. Here is a typical month's water usage and costs:

Fully allocating sewer services into the cost, a gallon of tap water = $ .00784. Yes, a gallon of tap water is less than 1 cent.

How does that 20 ounce bottle of Dasani compare? Dasani is $6.78 per gallon, so its gross profit margin relative to my cost of tap water is 99.9%.