its by volume its almost all water and sand, but they add all sorts of other things to it (biocides, scale inhibitors, friction reducers, corrosion inhibitors,

its by volume its almost all water and sand, but they add all sorts of other things to it (biocides, scale inhibitors, friction reducers, corrosion inhibitors, surfactants, etc.) and smarter people than me can tell you how bad that stuff is. off topic of fracing, but chemcically treating older wells is a pretty common thing as well (mostly acid treatments)