Why purify water?
Water from rivers, lakes and rain often contains mud, germs and dissolved chemicals. Drinking dirty water can cause diseases such as cholera and diarrhoea. Water purification is the process of removing these impurities to make water clean and safe to drink.
Methods of water purification
Several methods can be used, each removing different kinds of impurity:
- Filtration removes solid particles such as sand and mud.
- Boiling kills germs and microorganisms.
- Distillation removes dissolved solids and gives very pure water.
- Chlorination adds a small amount of chlorine to kill bacteria.
Example
At home, boiling tap water before drinking kills any germs that may still be present, making it safer to drink.
Water supply system
Clean water reaches our homes through a water supply system. At a water treatment plant, water passes through several steps:
- Screening removes large objects such as leaves.
- Sedimentation lets mud settle to the bottom.
- Filtration traps fine particles.
- Chlorination kills remaining germs.
The treated water is stored in a reservoir and pumped through pipes to homes, schools and factories.
Remember
- Filtration removes solids, boiling kills germs.
- Distillation gives the purest water.
- We must save water and avoid polluting our water sources.