For Luke, the situation is somewhat complicated by John the Baptizer, and he must deal with that first. With John, it's the water. The reversal emphasizes while it seems to ignore. And, through a series of short comments concerning water, the effect is strengthen. Rain, snow, sleet are all variations of a theme.
Water is the universal detergent.
But, we're making our water dirty so fast, we can actually see the results of our handiwork. A river in the mid-West was so polluted, that it caught fire and burned for three days. The fight for heavy water was most intense in Norway during World War 11. A cubic foot of water weighs 62.4 pounds. The world's fresh-water lakes hold about 30,000 cubic miles of water.