Potable water

Water is essential for life. Water that is safe for humans to drink is called potable water. Potable water is not pure water because it almost always contains dissolved impurities.

For water to be potable, it must have sufficiently low levels of dissolved salts and microbes. This is because:

  • dissolved salts can sometimes be harmful for humans
  • microbes can cause illnesses

Potable water in the UK

The methods used to make water potable depend on where you live. Starting with fresh water is easier than sea water, as removing the large amount of sodium chloride present in sea water requires a lot of energy.

In the UK, rain provides enough fresh water to meet the needs of the population. Sometimes during the summer months in some areas of the UK, water reserves run low and people are encouraged to conserve tap water by the use of hosepipe bans.

Rainwater collects in rivers, lakes and in rocks underground. This water contains low levels of dissolved substances.

Most potable water in the UK is produced from naturally occurring fresh water by:

  1. passing the water through filter beds to remove insoluble particles
  2. sterilising the water to kill microbes

The methods used for sterilisation include chlorine, ozone and ultraviolet light.