Glossary Item

Chlorine-containing compounds are described as having a certain percentage of "active" (or available) chlorine. It is the active chlorine in these products that kills microorganisms. The amount of active chlorine is usually described as a percentage, and differs from one product to another. Sodium hypochlorite is available as Milton^® solution (1 % sodium hypochlorite) or domestic bleach (typically between 4-5 % sodium hypochlorite). You can use any concentration to make a diluted chlorine solution by using the following formula:

[% chlorine in liquid bleach divided by target %] minus 1 = parts of water for each part* bleach

Example: To make a 1 % sodium hypochlorite solution from a 4 % chlorine concentrate, you must use 1 part chlorine and 3 parts water: [4 % divided by 1 %] minus 1 = [4] minus 1 = 3 parts water for each part chlorine

Note:
"Parts" can be used for any unit of measure (e.g., millilitres or litres) and need not even represent a defined unit of measure (e.g. container).