1. Natural Sciences and Technology Grade 6
Term 2: Matter and Materials
Processes to Purify Water
(ppt 2)

2. Topic 6 Processes to Purify Water
Treatment of Municipal Water
Gr. 6 Natural Sciences and Technology – Term 2, Topic 6

3. How is water cleaned by municipalities?
Tap water does not start off clean.
The process of cleaning it is called water treatment.
This usually happens in a water treatment plant.
Gr. 6 Natural Sciences and Technology – Term 2, Topic 6

4. Water treatment
Gr. 6 Natural Sciences and Technology – Term 2, Topic 6

5. Water treatment processes
Water is treated through a number of processes such as:
Step 1: Screening
Screening for obvious pollutants – water passes through a screen that is like a huge sieve.
Step 2: Settling
Settling is when the water and other pollutants sink to the bottom of the tank.
Gr. 6 Natural Sciences and Technology – Term 2, Topic 6

6. Water treatment processes
Step 3: Aeration
Aeration is when useful bacteria are used to break down pollutants and air is pumped into the water to keep the bacteria alive.
Step 4: Filtering
Filtering is when water is put through a filter of sand and gravel.
Step 5: Disinfection
Disinfection is when chemicals are added to the water to kill harmful germs.
Gr. 6 Natural Sciences and Technology – Term 2, Topic 6