High levels are most dangerous to children age one and under. Excessive levels of nitrate may react with hemoglobin in the blood to produce "blue baby" syndrome. Nitrate is an oxidized form of nitrogen that may be produced by bacteria converting nitrites to nitrates. High levels of nitrates in water may indicate biological wastes in the final stages of stabilization, or run off from heavily fertilized fields. The Texas Commission on Environmental Quality (TCEQ) and EPA set the maximum contamination level for nitrates at 10mg/L.
Nitrites are an intermediate stage in the decomposition of compounds containing nitrogen. Nitrites easily convert to nitrates in the presence of oxygen, so that nitrites are rarely found in surface water. Water containing large amounts of nitrite indicates that the water contains partially decomposed organic matter. Some home loan agencies require nitrite testing as part of the inspection process.
Excessive lead levels in the body can cause serious damage to the brain, nervous system, kidneys and red blood cells. Young children are especially vulnerable to lead poisoning. Most lead in household water comes from the plumbing rather than the water supply. Plumbing installed before 1930 is likely to contain lead. Newer copper pipes are frequently soldered with lead; in fact, lead solder is thought to be the leading cause of lead contamination in U.S. home water supplies. New brass faucets and fittings can also leach lead, even if they are called "lead free". Any factors that increase water corrosivity increase lead leaching off plumbing into the water. If the water is not corrosive, mineral deposits gradually coat pipe interiors, insulating the water from lead solder. This explains why new homes have a higher risk of lead contamination during the first five years, before any minerals have built up on the plumbing.
To reduce your risk of lead exposure in drinking water:
In addition to adversely affecting the taste of water, high sulfate levels can have a strong laxative effect, especially on people not used to water with increased sulfate levels. Concentrations above 200 mg/L also increase the amount of lead leached from lead pipes. The EPA has set acceptable sulfate levels at 250 mg/L or less.
The EPA guideline for drinking water sodium is 20 mg/L. This is a very low level, chosen because long-term exposure may increase blood pressure in susceptible individuals. Excessive sodium may also produce a salty taste. The World Health Organization has a maximum contaminant level (MCL) of 200 mg/L for sodium. TNRCC does not currently have a standard for sodium.
Fluoride occurs naturally in some ground waters. Public water supplies are generally supplemented with fluoride to maintain a level of 1 mg/L and aid in the prevention of dental caries. Fluoride levels of 2 mg/L may cause a brownish discoloration of the teeth, while levels of 4 mg/L or greater are considered toxic and associated with skeletal damage. Fluoridation is controversial. While studies have shown fluoride to decrease the incidence of tooth decay, other studies link fluoridation with increased rates of bone and joint disease.
Drinking water normally contains low concentrations of copper, with concentrations over 1 mg/L producing a bitter taste. High levels of copper are toxic and may be associated with gastrointestinal distress and Wilson's disease. High copper levels also contribute to plumbing corrosion and porcelain staining.
Calcium, Magnesium & Total Hardness
Water hardness is caused by dissolved minerals, mainly calcium and magnesium, but ions of iron, zinc, manganese, etc. may also be present. Excessively hard water limits the effectiveness of soaps and detergents, and may build up as a coating in plumbing.
Low water hardness is associated with an increased risk of cardiovascular disease, perhaps due to deficiencies of calcium and magnesium.
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