Appendix 15. Preparation and use of chlorine solutions

15.1 Preparation

• Work in a well ventilated room or, better still, outside in the shade but protected from the wind.
• Wear personal protective equipment (Section 7.5.3).
• Prepare solutions with clean, cold (or room temperature) water, in plastic containers only (corrosion of metal, inactivation of chlorine).
• Respect the recommended dilutions (an over-diluted product is less active; an over-concentrated product can cause irritation and corrosion).
• Use a clean, dry, plastic or glass receptacle to measure the dose of product or the measurer (e.g. measuring spoon) provided by the manufacturer.
• Pour the amount of water required into a container then add the product (and not the other way round) without splashing. Mix well using a clean stirrer used only for this purpose.
• Do not add any other product (e.g. a detergent) to chlorine solutions.
• For calcium hypochlorite, leave the solution to rest for a few minutes and only use the supernatant. Transfer the supernatant into another receptacle and discard the calcium residue into a waste pit after each preparation.
• Label the containers, specifying the chlorine concentration.

15.2 Use

Chlorine solutions are inactivated by the presence of organic matter (such as blood and other biological liquids, secretions or excreta, or dirt).
The WHO and CDC recommend cleaning objects, floors, surfaces, laundry with detergent and water before applying chlorine solution. This helps prevent the inactivation of chlorine.
Chlorine is also a bleaching agent. Use 0.05% chlorine solution to disinfect laundry and not a 0.2% solution which discolours it.
The disinfection of objects, floors and surfaces requires 15 minutes of contact time. Laundry must also be soaked for 15 minutes, but not longer.
Do not rinse afterwards objects, floors and surfaces disinfected with chlorine solutions, except stainless steel surfaces that must be imperatively rinsed (risk of corrosion).

15.3 Storage

Solid products

• Store in air-tight non-metallic containers, away from heat, light and humidity in a ventilated area.
• Carefully close containers after use.
• Never place them in contact with water, acid, fuel, detergents, organic or inflammable materials (e.g. food, paper or cigarettes).
• Never mix NaDCC with calcium hypochlorite (risk of toxic gas or explosion).
• NaDCC is more stable than calcium hypochlorite.

Prepared solutions

Change solutions every day. Do not prepare too much solution at a time (to avoid wasting unused solution). 

If preparing large quantities (e.g. 120 litre containers), preferably use a receptacle marked with a graduation corresponding to the necessary quantity of product (e.g. a cup with a mark corresponding to 110 g of NaDCC to prepare a 120 litre container of 0.05% chlorine solution).

Note:
Liquid bleach (sodium hypochlorite solution) should be reserved for domestic use only (e.g. homes, collective facilities likes schools or orphanages where a case has been declared), when the population is familiar with the product. There are various commercial forms of bleach under different names, different concentrations and different packaging.
To prepare a 0.2% chlorine solution the concentration of the bleach to be used, expressed in “active chlorine” on the commercial product, must be taken into account. The following formula is used to calculate the amount of water per quantity of bleach:

% of chlorine in liquid bleach ÷ % chlorine desired – 1.

The volume can be a litre, a gallon, a glass or any other recipient used to measure a dose.
These solutions must be prepared just before use.