There are many things in soda, and very few if any are good. Soda contains the following: sugar, caffeine, phosphorous, aspartame, and carbon acids. Soda does contain some water, but not enough to be good for you.
1 Additional Answer
If you are asking about soda drinks, they contain a high fructose corn syrup, additive dye, acid and caffeine. One can of soda has about ten to twelve teaspoons of sugar which is equal to 40-48 grams. Some drinks contain more such as Mt. Dew.