Common concerns for Illinois citizens in regard to their water quality:
Nitrate -- May be an indication of water contamination if found at unusual levels, because it is usually found in water that has come in contact with fertilizer or animal wastes.. Infants under 6 months in age are the most susceptible to excessive nitrates. The stomachs of infants allow for the conversion of nitrate to nitrite, which can cause asphyxiation when it reacts with hemoglobin in the blood. The drinking water standard for nitrate as nitrogen is 10 mg/L. Reverse osmosis or distillation can remove nitrate if necessary.
Hardness -- A measure of the amount of calcium and magnesium, found naturally in the water, and resulting in accumulation of scale on fixtures and in plumbing. Also increases the amount of detergent necessary to produce a lather. A water softener removes hardness and exchanges it for sodium.
Sulfur -- "Rotten-egg" odor is not a health concern in drinking water but is unpleasant to smell and can cause gray or black tarnish and stains. Carbon filtration or oxidation is used to eliminate sulfur odor.
Iron -- At levels greater than 0.3 mg/L, can stain laundry and porcelain. A water softener or oxidizing filter can remove iron from water.
Salty or Bitter Taste -- Due to a large amount of dissolved minerals, such as sodium, chloride, and sulfate in the water. Excessive minerals are removed from water by reverse osmosis or distillation.
Coliform Bacteria -- An indicator organism used to determine if water is likely to contain pathogens found in the intestinal tract of warm-blooded animals. Ideally, water should contain no coliforms. The water source should be protected so coliforms do not enter the water.
Lead -- Typically due to contact of water with plumbing components, it can accumulate in the body and cause organ and nervous system problems. Flushing the water until it is as cold as it can get usually eliminates lead from the plumbing system. The lead action level for public water supplies is 0.015 mg/L (equivalent to 15 ug/L).
Pesticides -- An indication of surface contamination. Many pesticides have various drinking water standards associated with them. Proper construction should keep pesticides out of the water, but if this is not successful then pesticides can usually be removed by carbon filtration or reverse-osmosis.
Arsenic -– Occurs naturally in the ground as a mineral in Illinois or may be found due to industrial activity. The drinking water standard for arsenic is 10 ug/L, and it is a carcinogen when found at levels above the standard. Some type of demineralization, such as reverse-osmosis or distillation, would be necessary to remove arsenic.