Household Water Treatment and Safe Storage Factsheet: Source ...

Household Water Treatment and Safe Storage
Fact Sheet: Chlorine (NaDCC Tablets)
The Treatment Process
Potential Treatment Capacity
Very Effective For: Somewhat Effective For: Not Effective For:
Bacteria
Viruses
Some protozoa
Helminths
Cryptosporidium parvum
Toxoplasma oocysts
Turbidity
Chemicals
Taste, odour, colour
What is NADCC?
Chlorine began to be widely used as a
disinfectant in the early 1900’s. It
revolutionized drinking water treatment and
dramatically reduced the incidence of
waterborne diseases. Chlorine remains the
most widely used chemical for water
disinfection in the United States.
NaDCC also known as sodium
dichloroisocyanurate or sodium troclosene,
is one form of chlorine used for disinfection.
It is often used to treat water in
emergencies, and is now widely available for
household water treatment.
Tablets are available from Medentech Ltd.
with different NaDCC contents (e.g. 2 mg to
5 g) to treat different volumes of water (e.g.
1 to 2,500 litres) at a time. They are usually
effervescent, allowing the smaller tablets to
dissolve in less than 1 minute.
How Does It Remove Contamination?
When added to water, NaDCC releases
hydrochlorous acid which reacts through
oxidization with microorganisms and kills
them.
Three things can happen when chlorine is
added to water:
1. Some chlorine reacts through
oxidization with organic matter and the
pathogens in the water and kills them.
This portion is called consumed
chlorine.
2. Some chlorine reacts with other organic
matter, ammonia and iron and forms
new chlorine compounds. This is called
combined chlorine.
3. Excess chlorine that is not consumed or
combined remains in the water. This
portion is called free residual chlorine
(FRC). The FRC is the most effective
form of chlorine for disinfection
(particularly for viruses) and helps
prevent recontamination of the treated
water.