2. Hard Water When washing with soap, do you find that the soap does not lather or leaves a floating scum on the surface of the water? This is HARD WATER It does not pose a health risk

3. How does hard water form? Some rocks, such as limestone contain minerals that will dissolve in water These minerals include ions of: calcium, magnesium, iron and manganese When slightly acidic water flows through limestone, more of these ions dissolve in the water

4. What is soap scum? When soap mixes with soft water, it forms a cloudy solution with a layer of suds on top In hard water, soap reacts with calcium and magnesium ions to form a precipitate This is the “scum”

5. What is scale? If your home water contains the ion hydrogen carbonate, HCO 3 -, it can form calcium hydrogen carbonate Ca(HCO 3 ) When you boil water with calcium hydrogen carbonate, you get scale This prevents heat to be transferred in the water

6. How to ‘soften’ hard water We used to add washing soda (sodium carbonate), which would precipitate the calcium and magnesium Water softening tanks contain resin that has Na ions, to create a precipitate Soda-lime process  use washing soda and lime (Ca(OH) 2 ) to precipitate out calcium and magnesium

7. Dissolved Oxygen Gases also dissolve in water Aeration  when turning water absorbs oxygen from the air The proper amount of oxygen needs to be present in water in order for aquatic organisms to survive

8. Polluted Water There are 3 types of contaminants the contribute to water pollution Physical Biological Chemical

9. Physical Contaminants Do not dissolve in water Ex. Oil, garbage, tree branches To remove: Coarse screens Skimmers Filters

10. Physical Contaminants

12. Biological Contaminants Bacteria and viruses Ex. E. Coli Ex. Walteron, Ontario- Runoff from cattle manure To remove Chlorination systems: use chlorine to bleach water

14. Chemical Contaminants Do dissolve in water Ex. Man-made chemicals, metals ions, fertilizers, pesticides To remove: The environment can break down some ?????

16. The Solution Do not pour chemicals down the drain Paint, medication, batteries, cleaners Water-treatment plants Test water samples to ensure safe drinking water