See an updated list of Drinking Water Contaminants & their Maximum Contaminant Level at the U.S. Environmental Protection Agency.

EPA Drinking Water maximum contaminant level, its health effects and methods to improve the quality of the water

1,1,1-Trichloroethane (Organic Chemical): MCL: 0.2 milligrams per litre; Health Effect: Causes narcosis & probably cancer; Treatment: Granular activated carbon filter
1,1-Dichloroethylene (Organic Chemical): MCL: 0.007 milligrams per litre; Health Effect: Affects kidneys & liver, can cause cancer; Treatment: Granular activated carbon
1,2-Dichloropropane (Organic Chemical): MCL: 0.005 milligrams per litre; Health Effects: Affects lungs, liver & kidneys; Treatment: Granular activated carbon
1.2-Dicloroethane (Organic Chemical): MCL: 0.005 milligrams per litre; Health Effects: Damages kidneys, liver & can cause nausea; Treatment: Granular activated carbon
2,4,5-TP Silvex (Herbicide): MCL: 0.05 milligrams per litre; Health Effects: Affects nervous system, respiratory system, liver & kidneys, can cause leukemia or cancer; Treatment: Granular activated carbon
2,4-D (Herbicide): MCL: 0.07 milligrams per litre; Health Effects: Affects nervous system, respiratory system, liver & kidneys, can cause leukemia or cancer; Treatment: Granular activated carbon
Alachlor (Herbicide): MCL: 0.002 milligrams per litre; Health Effects: Affects nervous system, respiratory system, liver & kidneys, can cause leukemia or cancer; Treatment: Granular activated carbon
Aldcarb (Pesticide): MCL: 0.003 milligrams per litre; Health Effects: Affects nervous system, respiratory system, liver and kidneys, can cause leukemia or cancer; Treatment: Granular activated carbon
Aldicarb Sulphone (Pesticide): MCL: 0.002 milligrams per litre; Health Effects: Affects nervous, respiratory system, liver & kidneys, can cause leukemia or cancer; Treatment: Granular activated carbon
Aldicarb Sulphoxide (Pesticide): MCL: 0.004 milligrams per litre; Health Effects: Affects nervous system, respiratory system, liver & kidneys, causes leukemia or cancer; Treatment: Granular activated carbon
Alpha Emitters (Radionuclide): MCL: 15 pci/L Curies per litre; Health Effects: Probable cause of cancer, affects skeletal tissue, & bone sarcomas; Treatment: RO, ion exchange, lime softening at a high PH
Aluminium (Contaminant): MCL: 0.05 to 0.2 milligrams per litre; Health Effects: Aesthetic, discolouration of water; Treatment: Ion exchange, RO, distillation
Aresenic (Inorganic Chemical): MCL: 0.05 milligrams per litre; Health Effects: Malignant tumors of skin & lungs, affects nervous system; Treatment: Activated alumina, ion exchange, lime softening, reverse osmosis, distillation
Asbestos (Inorganic Chemical): MCL: 7 MFL million fibres per litre; Health Effects: Probable cause of cancer; Treatment: Filtration, reverse osmosis, distillation
Atrazine (Herbicide): MCL: 0.003 milligrams per litre; Health Effects: Affects nervous and respiratory system, liver and kidney, probable cause of cancer; Treatment: Activated granular carbon
Barium (Inorganic Chemical): MCL: 2.0 milligrams per litre; Health effects: Affects nervous & circulatory systems; Treatment: Ion exchange, lime softening, reverse osmosis, distillation
Benzene (Inorganic Chemical): MCL: 0.005 milligrams per litre; Health Effects: Leukemia, anemia & possibly cancer; Treatment: Granular activated carbon
Beta Particle Emitters (Radionuclides): Max Level: 4 milligram per year; Health Effects: Probable cause of cancer, affects skeletal tissue, bone sacromas, head sacromas; Treatment: Reverse osmosis, ion exchange, lime softening at high pH
Cadnium (Inorganic Chemical): MCL: 0.005 milligrams per litre; Health Effects: Kidney disorders, bronchitis, anemia; Treatment: Ion exchange, reverse osmosis, lime softening, distillation, corrosion control
Carbofuran (Pesticide): MCL: 0.04 milligrams per litre; Health Effects: Affects nervous system, respiratory system, liver & kidneys, causes leukemia or cancer; Treatment: Granular activated carbon
Carbon Tetrachloride (Organic Chemical): MCL: 0.005 milligrams per litre; Health Effects: Affects nervous system, liver and digestive system, causes cancer; Treatment: Granular activated carbon
Chlordane (Pesticide): MCL: 0.002 milligrams per litre; Health Effects: Affects nervous system, respiratory system, liver & kidneys, causes leukemia or cancer; Treatment: Granular activated carbon
Chloride (Contaminant): MCL: 250 milligrams per litre; Health Effects: Taste, smell, corrosion of pipes; Treatment: Ion exchange, RO, distillation
Chromium (Inorganic Chemical): MCL: 0.1 milligrams per litre; Health Effects: Liver and kidney disorders, affects skin and digestive system; Treatment: Ion exchange, lime softening, reverse osmosis, distillation
Colour (Contaminant): MCL: 15 TCU total colour units; Health Effects: Aesthetic, staining; Treatment: Sediment filter with granular activated carbon filtration
Copper (Inorganic Chemical): MCL: 1.3 milligrams per litre; Health Effects: Stomach and intestinal distress; Treatment: Ion exchange, RO, distillation
Dibromochloropropane (Organic Chemical): MCL: 0.0002 milligrams per litre; Health Effects: Probable cause of cancer; Treatment: Granular activated carbon
Endrin (Pesticide): MCL: 0.002 milligrams per litre; Health Effects: Affects nervous system, respiratory system, liver & kidneys, causes leukemia or cancer; Treatment: Granular activated carbon
Ethylene Dibromide (Organic Chemical): MCL: 0.00005 milligrams per litre; Health Effects: Probable cause of cancer; Treatment: Granular activated carbon
Ethylbenzene (Organic Chemical): MCL: 0.7 milligrams per litre; Health Effects: Affects nervous system, liver and kidneys; Treatment: Granular activated charcoal
Fluoride (Inorganic Chemical): MCL: 4.0 milligrams per litre; Health Effects: Brown discolouration of teeth; Treatment: Ion exchange, reverse osmosis, distillation, activated alumina
Foaming Agents (Contaminant): MCL: 0.5 milligrams per litre; Health Effect: Aesthetic; Treatment: Carbon filtration, distillation
Giardia Lamblia (Microbiological): MCL: Zero colonies; Health Effects: Stomach cramps, intestinal distress (Giardiasis); Treatment: Filtration, chlorination, UV radiation, distillation
Heptachlor (Pesticide): MCL: 0.0004 milligrams per litre; Health Effects: Affects nervous system, respiratory system, liver & kidneys, causes leukemia or cancer; Treatment: Granular activated carbon
Heptachlor Epoxide (Pesticide): MCL: 0.0002 milligrams per litre; Health Effects: Affects nervous system, respiratory system, liver & kidneys, causes leukemia or cancer; Treatment: Granular activated carbon
Iron (Contaminant): MCL: 0.3 milligrams per litre; Health Effects: Taste, staining, scaling, discolouration of water; Treatment: Ion exchange, chlorination, filtration, distillation
Lead (Inorganic Chemical): MCL: 0.015 milligrams per litre; Health Effects: Affects nervous & reproductive system and kidneys, causes hypertension; Treatment: Ion exchange, reverse osmosis, distillation, activated carbon granular filter (preferably carbon block filter)
Legionella (Microbiological): MCL: Zero colonies; Health Effects: Causes Legionnaires disease, Pontiac fever; Treatment: Filtration, chlorination, UV radiation
Lindane (Pesticide): MCL: 0.0002 milligrams per litre; Health Effects: Affects nervous system, respiratory system, liver & kidneys, causes leukemia or cancer; Treatment: Granular activated carbon
Manganese (Contaminant): MCL: 0.05 milligrams per litre; Health Effects: Taste, staining, scaling, discolouration of water; Treatment: Ion exchange, chlorination, filtration, distillation
Mercury (Inorganic Chemical): MCL: 0.002 milligrams per litre; Health Effects: Affects nervous system, kidneys; Treatment: Granular activated carbon, lime softening, reverse osmosis, distillation
Methoxychlor (Pesticide): MCL: 0.04 milligrams per litre; Health Effects: Affects nervous system, respiratory system, liver & kidneys, causes leukemia or cancer; Treatment: Granular activated carbon
Monochlorovenzene (Organic Chemical): MCL: 0.1 milligrams per litre; Health Effects: Affects nervous system, kidneys and liver; Treatment: Granular activated carbon
Nitrate (Inorganic Chemical): MCL: 10 milligrams per litre; Health Effect: Methmoglobinemia; Treatment: Ion exchange, RO, distillation
Nitrite (Inorganic Chemical): MCL: 1.0 milligram per litre; Health Effect: Methmoglobinemia; Treatment: Ion exchange, RO, distillation
Odour (Contaminant): MCL: 3 ton total odour units; Health Effects: Aesthetic; Treatment: Activated granular carbon
Pentachlorophenol (Herbicide): MCL: 0.001 milligrams per litre; Health Effects: Affects nervous system, respiratory system, liver & kidneys, causes leukemia or cancer; Treatment: Granular activated carbon
Radium 226 & 228 (Radionuclides): MCL: 5 pci/L pico Curies per litre; Health Effects: Probable cause of cancer, affects skeletal tissue, & bone sarcomas; Treatment: RO, ion exchange, lime softening at a high pH
Selenium (Inorganic Chemical): MCL: 0.05 milligrams per litre; Health Effects: Affects nervous system, causes irritation to the mucous membrane; Treatment: Distillation, lime softening, reverse osmosis, activated alumina
Silver (Contaminant): MCL: 0.1 milligrams per litre; Health Effects: Discolouration of skin; Treatment: Ion exchange, RO, distillation
Sodium (Inorganic Chemical): MCL: none (20mg/L makes water too salty); Health Effects: Possible increased blood pressure in susceptible individuals; Treatment: Distillation, RO, ion exchange
Styrene (Organic Chemical): MCL: 0.1 milligrams per litre; Health Effects: Affects nervous system, liver and kidney; Treatment: Granular activated carbon
Sulfate (Contaminant): MCL: 250 milligrams per litre; Health Effect: Taste, laxative effects; Treatment: Ion exchange, RO, distillation
Tetrachloroethylene (Organic Chemical): MCL: 0.005 milligrams per litre; Health Effects: Affects nervous system, probable cause of cancer; Treatment: Granular activated carbon
Trihalomethanes (Organic Chemical): MCL: 0.1 milligrams per litre; Health Effects: Affects nervous system, probable cause of cancer; Treatment: Granular activated carbon
Turbidity (Contaminant): MCL: 0.5 - 1.0 NTU Turbidity Units; Health Effects: Interferes with disinfection; Treatment: Filtration, granular activated carbon, distillation, reverse osmosis
Vinyl Chloride (Organic Chemical): MCL: 0.002 milligrams per litre; Health Effects: Affects nervous system, probable cause of cancer; Treatment: Granular activated carbon
Xylenes - total (Organic chemical): MCL: 10 milligrams per litre; Health Effects: Affects nervous system, kidneys, lungs, liver and mucous membranes; Treatment: Granular activated carbon
Zinc (Contaminant): MCL: 5.0 milligrams per litre; Health Effects: Taste; Treatment: Ion exchange, reverse osmosis, distillation

Suggested treatments given above are only some of the methods. Sometimes one method by itself is adequate but at times a combination of methods is needed. Under some treatments a choice of methods is given. Consult your local water treatment company for the best recommendation of treatment method.

MCL: Maximum Contaminant Level