The liquids used in fracking are suspensions of water, support agents such as quartz sand or ceramic support grains as well as additives. The concentration and number of chemicals used is selected on a site-specific basis. In most cases, the proportion of additives in the total liquid is less than 1% to 5%. The solids should keep the artificially created cracks open after stimulation so that the natural gas can flow into the well.
According to a publication by the US Environmental Protection Agency (EPA), up to 600 different organic and inorganic substances were used in the USA. This represents the palette from which the compositions are selected site-specifically. Up to 20 different substances were used in one stimulation. In Germany, a total of around 120 chemicals used are known for the period from 1983 to 2011. The companies are currently developing new fluids in which the number of chemicals used is reduced and the additives used do not exceed water hazard class 1.