The following is a list of common water
contaminants found in both public and private drinking water supplies across the
U.S. and Canada, together with their health effects and the most appropriate treatment
methods for their removal. For more information on a particular contaminant or
treatment method, please click on the name of the item.
Please note: This
list was compiled for research and informational purposes only. It is not intended
to suggest that any of the listed contaminants are present in your water supply.
Only testing by an accredited lab can identify the presence of contaminants in
your water supply.
Contaminant Name | Maximum
Acceptable Level | Common Sources | Health
Effects | Most Effective Purification Tech. |
| Arsenic | 0.010 mg/L | Natural deposits, smelters, glass,
electronics wastes, orchards | Skin, nervous system toxicity | Reverse
Osmosis |
| Asbestos | 7 MFL (million fibers / liter) | Natural
deposits, asbestos cement in water systems | Cancer | Reverse Osmosis,
Activated Carbon |
| Barium | 2 mg/L | Natural deposits,
pigments, epoxy sealants, spent coal | Circulatory system effects | Reverse
Osmosis |
Bacteria / Coliform | - | animal &
human waste, septic fields, sewage, farming | various illnesses | Ultraviolet |
| Cadmium | 0.005 mg/L | Natural deposits, galvanized pipe
corrosion, batteries, paints | Kidney disorders | Reverse Osmosis |
| Chloradane | 0.002 mg/L | Leaching from soil treatment for
termites | Cancer | Activated Carbon |
| Chlorine | 4
mg/L | Water disinfection | see chlorination by-products (Trihalom
ethanes) | Activated Carbon, KDF |
| Chromium | 0.1
mg/L | Natural deposits, mining, electroplating, pigments | Liver,kidney,
circulatory disorders | Reverse Osmosis |
| Copper | 1.3
mg/L | Natural / industrial deposits, wood preservatives, plumbing | Gastrointestinal
irritation | Reverse Osmosis, KDF |
| Cryptosporidium | Zero | Animal
or human waste, contaminated food products | Gastrointestinal illness | Reverse
Osmosis, Carbon Block (0.5 micron) |
| E.coli | Zero | Naturally
occurring, human or animal wastes | Gastrointestinal disorders (often
severe) | Ultraviolet |
| Fluoride | 4 mg/L | Natural
deposits, fertilizer, aluminum industries, water additive | Skeletal and
dental fluorosis | Reverse Osmosis |
| Giardia | Zero | Naturally
occurring, human or animal wastes | Gastrointestinal disorders (Beaver
Fever) | Reverse Osmosis, Carbon Block (0.5 micron) |
| Hydrogen Sulfide | n/a | Natural deposits | Rotten egg
taste and odour | Manganese Greensand Filter, KDF |
| Iron | 0.3
mg/L | Natural deposits | Staining of laundry, plumbing,
appliances | Iron Reduction Filter |
| Manganese | 0.05
mg/L | Natural deposits | Staining of laundry, plumbing,
appliances | Iron Reduction Filter |
| Mercury | 0.002
mg/L | Crop runoff, natural deposits, batteries, electrical switches | Kidney,nervous
system disorders | Reverse Osmosis, Activated Carbon |
| Microbiological
Contaminants | - | animal & human waste, septic fields, sewage,
farming | various illnesses | Various |
| Nitrate /
Nitrite | 10 mg/L | Animal waste, fertilizer, natural deposits, septic
tanks, sewage | Methemoglo bulinemia (blue baby syndrome) | Reverse
Osmosis |
| PCB | 10.0005 mg/L | Coolant oils from
electrical transformers, plasticizers | Cancer | Activated Carbon |
| Radium | 5 pCi/L | Natural deposits | Bone cancer | Reverse
Osmosis |
| Radon | | Natural deposits | Cancer | Activated
Carbon |
| Selenium | 0.05 mg/L | Natural deposits,
mining, smelting, coal/oil combustion | Liver damage | Reverse Osmosis |
| Total Dissolved Solids | 500 mg/L | Erosion of naturally
occurring mineral deposits | Gastrointestinal irritation in some individuals | Reverse
Osmosis |
| Toxaphene | 0.003 mg/L | Insecticide formerly
used on cattle, cotton, soybeans | Cancer | Activated Carbon |
| Trihalomethanes (THMs)(chlorination by-products) | 0.08 mg/L | By-product
of chlorination in drinking water | Cancer | Activated Carbon, KDF |
| Turbidity | n/a | Soil runoff | Interferes with
disinfection, filtration | Whole-House Sediment Filter, Reverse Osmosis |
| Uranium | 0.03 mg/L | Natural occurring | Kidney
disorders, cancer | Reverse Osmosis |
| Viruses | - | animal
& human waste, septic fields, sewage, farming | various illnesses | Ultraviolet |
| Volatile Organic Compounds (VOCs) | Varied | Varied | Varied,
incl. cancer | Activated Carbon |
| Zinc | 5 mg/L | Natural
deposits, industrial waste | Metallic taste in water | Reverse
Osmosis, KDF |