Why do you have to put all those chemicals in the water you use to frack?

It is important to note that the chemical additives used in the fracturing process represent less than .5 percent of the total fluid. The overwhelming majority of the fluid is comprised of water and sand. These additives are used for a variety of reasons. Fracturing fluids include biocides to control bacteria from forming in the well; a corrosion inhibitor is required to prevent the steel casing from rusting and jeopardizing the integrity of the steel and a friction agents or a surfactant is used to reduce the friction when the fluid is pumped down the wellbore at very high pressures. The following chart from FracFocus.org, the national chemical registry, goes into a bit more detail on the various additives that you may find helpful: