Potable Water

Summary: Water that is safe to drink. It may contain dissolved minerals but must be free from harmful microorganisms and toxic substances. Tags: igcse chemistry definition environmental-chem Created: 2026-07-14 Last Updated: 2026-07-14

Potable water is water that is safe for human consumption, meaning it is free from harmful microorganisms and toxic substances, though it may still contain dissolved minerals and salts that give it taste and nutritional value. It is important to distinguish potable water from chemically pure water — pure water contains only H₂O molecules and boils at exactly 100 degrees Celsius at 1 atm, while potable water contains dissolved ions and boils over a temperature range. The standard treatment process for making fresh water potable involves three main stages: sedimentation to allow large suspended particles to settle, filtration through sand and gravel beds to remove finer solids, and chlorination to kill bacteria and other pathogenic microorganisms. In coastal regions where freshwater is scarce, desalination by distillation or reverse osmosis may be employed to obtain potable water from seawater, though these processes are energy-intensive and expensive. In IGCSE exams, remember that the boiling point test distinguishes pure water from potable water, and that potable water is not the same as pure water — it is safe to drink but still contains dissolved substances.

Key term — IGCSE Chemistry (0620/0971) glossary.