I think this is an extremely clever advertisement from Denver Water. This campaign for the company that supplies most of the water in the Denver area is really successful of getting the point across while also creating an interest. As you can see from the photo, the ad uses only a small amount of space on the billboard. This, I feel, is to get the point across that people only have to pay what they use, rather than a flat rate. This creates a movement to be more efficient with the water, as well as letting consumers know that they wont be charged an arm and a leg even when they use only a little bit of water.

Denver Water also advertised this same idea using a park bench. The park bench only had a seat and back for one person to sit and had the phrase "Use only what you need" on it as well.

Overall, very creative and interesting.