What does chlorinated mean?
Chlorinated describes something — most commonly water — that has been treated with chlorine, a reactive greenish-yellow element prized for its ability to destroy bacteria and other microorganisms. The word is encountered daily in ordinary life: public drinking supplies, swimming pools, and hot tubs all rely on chlorinated water to stay safe and hygienic. In chemistry, it also refers more broadly to compounds into which chlorine atoms have been incorporated, such as certain industrial solvents. The term derives from the Greek 'chloros' (pale green), the color of chlorine gas when first isolated in the early nineteenth century. While chlorination has arguably saved millions of lives by curbing waterborne disease, heavily chlorinated water carries a distinctive smell and taste, and some people find it harsh on skin and eyes. As a word, it is neutral and practical, belonging equally to technical manuals and everyday conversation.
Treated with or containing chlorine, especially for disinfection; also, chemically combined with chlorine atoms.
"She prefers filtered water because she finds chlorinated tap water tastes unpleasant."
Past tense and past participle of chlorinate: to have treated something with chlorine or combined it with chlorine.
"Engineers chlorinated the reservoir before returning it to service."
The word traces back to the Greek 'chloros', meaning pale green — the very color of chlorine gas itself.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of chlorinated
'Chlorinated' derives from 'chlorine', coined in the early nineteenth century by English chemist Humphry Davy from the Greek 'chloros', meaning pale yellow-green — the color of chlorine gas. The suffix '-ate' forms the verb 'chlorinate' (to treat with chlorine), and '-ed' produces this adjectival form. It shares its Greek root with other scientific terms such as chlorophyll, chloroplast, and chloroform.
Related word forms
How chlorinated is actually used
'Chlorinated' is chiefly a technical and everyday descriptive term with no strong register constraints; it appears both in chemistry writing and casual speech about swimming pools and drinking water. It is most often used attributively (chlorinated water) rather than predicatively.
Easily confused with chlorinated
A chloride is a chemical compound containing the chloride ion (such as sodium chloride, i.e., table salt), whereas 'chlorinated' describes something treated with the element chlorine.