Potable water
Water is essential for life. Water that is safe for humans to drink is called potableWater that is safe to drink.. Potable water is not pure water because it almost always contains dissolvedWhen something is broken up in a liquid and no longer exists. impurities.
For water to be potable, it must have sufficiently low levels of dissolved saltA compound formed by neutralisation of an acid by a base, eg a metal oxide, as the result of hydrogen ions in the acid being replaced by metal ions or other positive ions. Sodium chloride, common salt, is one such compound. and microbeMicroscopically small organism, such as a bacterium or single-celled fungus. Also called a microorganism.. 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 energyThe capacity of a system to do work or the quantity required for mechanical work to take place. Measured in joules (J). For example, a man transfers 100 J of energy when moving a wheelbarrow..
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:
- passing the water through filter beds to remove insolubleUnable to dissolve in a particular solvent. For example, sand is insoluble in water.particleA general term for a small piece of matter. For example, protons, neutrons, electrons, atoms, ions or molecules.
- steriliseTo kill any living organisms, usually microbes that might cause disease, on an object or in a substance. the water to kill microbes
The methods used for sterilisation include chlorine, ozone and ultraviolet light.