Potable Water

Water is essential for life. Potable water means water that is safe to drink.

Potable water is not pure in the chemical sense because it contains dissolved solid substances.

Pure water has a pH of ~7 and contains no dissolved substances.

The method to obtain potable water depends on the source.

The methods used to make water potable with fresh water is easier than sea water. This is because removing the large amount of sodium chloride present in sea water requires a lot of energy.

Fresh water is water that comes from rain.

In the United Kingdom, rain provides water with low levels of dissolved substances.

Rainwater collects in the ground, lakes and rivers.

Fresh water still needs to be treated before it is safe to drink.

Most potable water in the UK is produced from fresh water.

If supply of fresh water are limited, desalination of sea water may be required.

In warmer countries, drinking water mostly comes from groundwater because the fresh water dried up quickly.

Sterilising agents used for potable water are chlorine, ozone or ultraviolet light.

Fresh water is the easiest to make potable. This is done by passing the water through filter beds to remove solid particles then adding chlorine or using ultraviolet light to kill any harmful micro-organisms.

The two main steps used to trea t water from lakes are filtration and sterilisation to kill microbes.

Solid is separated from the reservoir water during filtration.

Some water companies add fluoride to drinking water because fluoride prevents dental disease and improves dental health.