Environmental Sciences: Inorganic Chemistry
Reporting and Interpretation
Most of the recommended limits or maximum contaminant levels (MCLs) for inorganics in public water supplies are as follows:
- Antimony - MCL = 0.006 mg/L. May decrease growth and longevity. Potential sources are industrial discharges or from tin/antimony solder used in plumbing.
- Arsenic - MCL = 0.010mg/L. Carcinogenic properties have been ascribed to arsenic. Its presence may be due to natural deposits, industrial discharges or pesticides.
- Barium - MCL = 2 mg/L. Occurs only in trace amounts in drinking water and rarely exceeds 1 mg/L.
- Beryllium - MCL = 0.004 mg/L. Beryllium is very poisonous. It is used in atomic reactors, aircraft, rockets and missile fuels. It is through discharges of such industries that it may enter water.
- Cadmium - MCL = 0.005 mg/L. Cadmium is toxic and may be carcinogenic. It may enter water as a result of industrial pollution or deterioration of galvanized pipe.
- Chloride - MCL = 250 mg/L. High chloride levels may harm pipes, as well as impart an unpleasant salty taste.
- Chromium - MCL = 0.10 mg/L. Chromium salts are used in industrial processes and may enter a water supply through industrial discharge.
- Copper - MCL = 1.3 mg/L. It may impart a metallic taste to water and cause greenish stains on faucets and plumbing fixtures.
- Cyanide - MCL = 0.2 mg/L. Can cause spleen, brain and liver damage. It is used in electroplating, steel processing, plastics, synthetic fibers, fertilizer and farm products.
- Fluoride - MCL = 4.0 mg/L. Fluorides are found mostly in groundwater as a natural constituent.
- Iron - MCL = 0.3 mg/L. Iron in water can cause staining of laundry and porcelain. It may give the water an astringent taste.
- Lead - MCL = 0.015 mg/L. Lead is a cumulative poison. In a water supply it may occur where piping material or pipe joint compound contains lead.
- Manganese - MCL = 0.05 mg/L. Manganese can cause objectionable stains to laundry and fixtures.
- Mercury - MCL = 0.002 mg/L. Mercury is very toxic and its presence may be associated with industrial water and agricultural applications.
- Nitrate - MCL = 10 mg/L (as nitrogen). Serious poisonings in infants have occurred following ingestion of well water containing nitrate nitrogen at concentrations greater than 10 mg/L. This problem is known as methemoglobinemia and is generally confined to infants less than three months old. The presence of nitrates is usually due to animal wastes and fertilizers. Boiling water does not remove nitrates but instead concentrates them.
- Nitrite - MCL = 1mg/L (as nitrogen). Nitrite is the actual etiologic agent of methemoglobenemia. It results from oxidation of ammonia or reduction of nitrates. May occur in natural water or water distribution systems.
- Nickel - MCL = 0.1 mg/L. May affect the heart and liver. Can enter water supplies through discharges from battery, ceramics, or glass production.
- pH - MCL = 6.5 - 8.5. A soft acid water may leach metals from plumbing causing staining problems, metallic tastes or deleterious health effects.
- Selenium - MCL = 0.05 mg/L. It is an essential trace nutrient, but may be toxic above trace levels. Natural levels in groundwater may be due to soil types. Selenium may be leached from coal ash and fly ash at electric power plants that burn seleniferous coal.
- Silver - MCL = 0.10 mg/L. Exposure to silver in drinking water may cause argyria (a discoloration of the skin). Health effects are only cosmetic.
- Sulfate - MCL = 250 mg/L. May naturally be present in groundwater. Its sodium and magnesium salts exert a cathartic action.
- Thallium - MCL = 0.002 mg/L. Affects the brain, kidneys, and liver. Its presence may be associated with electronics or glass industries.
- Total Dissolved Solids - MCL = 500 mg/L. Waters with high dissolved solids are unpalatable and may be unsuitable for many industrial applications.
- Zinc - MCL = 5 mg/L. Zinc may cause a bitter astringent taste and opalescence in alkaline water. Most often enters the water supply through the deterioration of galvanized iron pipes.
Sample analysis time will vary from one day to thirteen days, depending upon the number of parameters requested for the sample. The submitter should receive a copy of the analytical results within three weeks of the date of sample collection. Public and private water system laboratory reports are held for five years, and then destroyed.
Environmental Sciences Information