Reverse Osmosis
Water Education
& Your Health
Customer Reviews
& Testimonials
Talk to a WQA Certified
&Water Specialist
Welcome to APEC Water!

We are America's leading supplier of high quality drinking water systems and information source.
Charity Penguin

At APEC, we strive to provide the best drinking water available to everyone. Even if it means offering a free system to those in need.

Click here to learn more about our Free Drinking Water Donation Program.

Embracing Happiness





EXPERIMENT VI - Chlorination for Disinfection

Image Place Holder left

Chlorine is used in, both drinking water and wastewater treatment, as a disinfectant. Its germicidal action is due to the hypochlorous acid (HOCl) that forms when chlorine is added to water. Exactly how this acid exerts its killing power is not yet fully known. It possibly releases a reactive form of oxygen that combines with the protoplasm of the microbial cell and, therefore, destroys it. The hypochlorite ion OCl- also has some killing potential.

This experiment will help you understand what is the most effective concentration of chlorine for “killing” organisms in water. This experiment also explains why it is important to keep a residual concentration of chlorine in drinking water.

Material Needed:

  • Four 2-L bottles
  • Pond water
  • Bleach (NaOCl)
  • Microscopes
  • Slides
  • Stain (crystal violet)
  • Eye droppers
  • Stirring rods


  1. Use the first gallon bottle of collected water as a control.
  2. To the second bottle add 1 drop of NaOCl (bleach).
  3. To the third bottle add 2 drops of NaOCl.
  4. To the fourth bottle add 4 drops. Let them sit for 30 minutes.
  5. Make up some microscope slides with water from each bottle and observe.

Source: Enviromental Protection Agency

Related Articles:

EXPERIMENT V - Carbon Treatment for Water Pollution Control
EXPERIMENT VII - What is in the Source Water


Follow up on Twitter APEC Water - Twitter Or become our fans on facebook APEC Water - Facebook Social Network