There are three general types of additives.
Inorganic additives are generally strong acids or alkalis.
They are sometimes marketed on the basis of their ability to open clogged drains - they have the same active ingredients as popular drain cleaners. Packages of these materials usually bear warnings stating that they are caustic or corrosive. Organic solvents have also been sold as septic system additives. These products give off fumes, and their packages include warnings against breathing the vapors. Biological additives are mixtures of enzymes and harmless bacteria with a stabilizing agent to enhance product shelf life.