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Mixing of Chlorine Bleach Solution for Disinfecting

Household bleach (5.25% sodium hypochlorite) mixed with water, is an inexpensive and effective disinfectant. By mixing different amounts of bleach with water, you can make a high, intermediate, or low-level disinfectant.

High-level Disinfection: (1:10 dilution of bleach | 5000 ppm)

When to be used:

  • Cleaning up a large blood or body fluid spill.
  • When directed by public health.

How to mix the bleach solution:

  • 62 ml (1/4 cup) : 562 ml (2¼ cups) water, or
  • 250 ml (1 cup) : 2250 ml (9 cups) water

Intermediate-level Disinfection (1:50 dilution of bleach | 1000 ppm)

When to be used:

  •  For use in washrooms and change tables in child-care

How to mix the bleach solution:

  • 20 ml (4 teaspoons) household bleach + 1000 ml (4 cups) water, or
  • 100 ml (7 tablespoons) household bleach + 5000 ml (20 cups) water

Low-level Disinfection (1:500 dilution of bleach | 100 ppm)

When to be used:

  • Safe level for toys, dishes, utensils and food contact surfaces.

How to mix the bleach solution:

  • 1 ml (1/4 teaspoon) household bleach to 500 ml (2 cups) water, or
  • 20 ml (4 teaspoons) household bleach to 10 L (40 cups or approx. 2 gallons)


  • Cleaning must be done prior to disinfecting.
  • A bleach and water solution should be mixed daily to preserve its strength.
  • Leave the solution on the surface for a minimum of one minute. For high level disinfection a 10 minute contact time is recommended.
  • In the event of a respiratory or enteric (vomiting and/or diarrhea) outbreak, ensure to contact a member of the Health Unit’s Infectious Disease Team as soon as possible. A change in disinfectant type and strength may be required.
  • Please visit for an online chlorine dilution calculator to determine your own recipe.


  • Association for Professionals in Infection Control and Epidemiology, 2009
  • Public Health Ontario
  • Health Protection and Promotion Act. Ontario Regulation 562, Food Premises 1990