Sodium Etidronate is the sodium salt of etidronic acid. It is used as a chelating agent which binds to hard water metal ions and 'softens' the water. It is also used in medicine to strengthen bone and treat osteoporosis.
EWG score: The EWG score is a hazard score ranging from 1-2 (low hazard), 3-6 (moderate hazard) and 7-10 (high hazard) published by the Environmental Working Group. Their data is sourced from the Skin Deep® database and studies published in open scientific literature.