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