Water Purification
Science Practicals: GCSE, topic 2.1.14
Potable Water
We need to drink water to stay alive. However, water is often found with other substances dissolved in it. These substances can be harmful so we treat water to make it potable (safe for human consumption).
Reduce concentrations of microbes
- To make water potable, we need to drastically reduce the number of microbes found in it.
Reduce concentrations of dissolved minerals and salts
- To make water potable, we need to reduce the concentrations of dissolved minerals and salts found in the water.
- We do not eradicate the minerals and salts from the water completely.
Not chemically pure
- If water is potable, it does not mean that it has to be chemically pure (made up solely of H2O molecules).
Potable Water in the UK
There are different methods for producing potable water. Which method is chosen depends on what water is available and the local conditions.
Rainfall
- In the United Kingdom, levels of rainfall are quite high.
- Rain water is a type of fresh water, meaning that it contains low concentrations of dissolved substances.
Collecting fresh water
- Step 1 in potable water production in the UK is collecting fresh water from a suitable source (one that is not close to heavily polluted areas).
Treating water
- Once collected, the water is put through a 2-step treatment process:
- Filtration: passed through wire mesh to remove solid particles.
- Sterilisation: chlorine gas is added to kill harmful microorganisms.
Test yourself on Water Purification
What term describes water that is safe for human consumption?
Potable water contains a...
A glass of water is safe to drink but contains dissolved minerals and salts. Is this water chemically pure?
What are the names of these processes?
How does filtration differ from sterilisation when treating water?