Type of
Contamination

Sources of Contaminant in Drinking Water

Potential Health
Effects from Ingestion of Water

Reduction with Purity

Chlorine

Disinfectants

Eye/nose irritation, stomach discomfort, anaemia. Infants & young children: nervous system effects.

100%

Trihalomethanes
Chloroform 
Bromoform
Bromodichloromethane
Dibromochloromethane

Disinfection by-products.

Increased risk of cancer. Liver, kidney or central nervous system problems.

>95%

Microorganisms
Cryptosporidium
Giardia lambila
E.Coli

Human and animal faecal waste.

Gastrointestinal illness (e.g. diarrhoea, vomiting, cramps).
(There have been deaths caused by Cryptosporidium or E.Coli bacteria in water.)

100%

Viruses, parasites

Human and animal faecal waste.

Same as above. Can also cause nausea and associated headac­hes.

100%

VOC’s
Volatile Organic
Chemicals

Mainly herbicide runoff or discharge from chemical plants/factories.

Cancer, kidney, liver and brain damage. Damage to the nervous, reproductive and immune systems.

>85%*

BTX
Benzene

Discharge from factories, leaching from gas storage tanks and landfills.

Anaemia, decrease in blood pla­telets, increased risk of cancer.

>80%

Radon

Natural gases, (radioactive) element found in bedrock.

Increased risk of cancer.

100%