Tetrapotassium Pyrophosphate

Tetrapotassium pyrophosphate (TKPP) is an alkaline, water-soluble phosphate salt used in heavy-duty cleaners and industrial degreasers as a chelator and builder. It sequesters hard-water cations (calcium and magnesium) that would otherwise interfere with surfactant performance, and contributes alkalinity that helps saponify grease and oil.

Modern consumer detergent formulations have largely phased out phosphates because of the eutrophication concern — when phosphorus reaches surface water, it drives algal blooms that deplete oxygen and harm aquatic life. Industrial-strength degreasers like Simple Green Pro HD still use small amounts (<1%) of TKPP for cleaning performance; the drain-destined automotive use case puts that phosphorus into the wastewater stream where treatment plants generally remove most of it, but the regulatory pressure on phosphates is the reason this ingredient appears at trace concentrations rather than dominant ones.