Water Treatment and Potable Water

This lesson covers the production of potable water, waste water treatment and desalination, as required by the Edexcel GCSE Chemistry specification (1CH0, Topic 1). You need to understand the difference between potable water and pure water, describe the steps in water treatment, and know when and how desalination is used.

---

Potable Water vs Pure Water

It is important to understand the distinction between potable water and pure water:

Term	Definition
Pure water	Contains only H\u2082O molecules and nothing else. Has a boiling point of exactly 100 \u00b0C and a melting point of exactly 0 \u00b0C.
Potable water	Water that is safe to drink. It is not pure — it contains dissolved minerals and other substances, but the levels of these are low enough to be safe for human consumption.

• Pure water is very difficult and expensive to produce. It requires distillation.
• Potable water is what comes from the tap. It contains low levels of dissolved salts and microorganisms have been killed, but it still contains dissolved substances.