Lead in Water

Lead in Water

Lead is rarely found in natural sources of water such as rivers and lakes or underground aquifers.

Contact with lead can be through paint, water pipes, dust, soil, food, hobbies, or your job. You can’t see, smell, or taste lead, so even water that runs clear can contain it.

Lead can enter drinking water when plumbing materials that contain lead corrode, especially where the water has high acidity or low mineral content that corrodes pipes and fixtures. The most common sources of lead in drinking water are old lead pipes, faucets, and fixtures.

The simplest explanation is that when plumbing pipes and fixtures containing lead corrode, the lead can dissolve or flake into the water that flows from our faucets.

Lead is not among the metals considered essential to the nutrition of animals or human beings.

In soft water, lead may be very toxic. In hard water, equivalent concentrations of lead are less toxic.

The National Institute of Environmental Health Sciences reports that no amount of lead in the blood is safe. It is known that levels as low as 5 micrograms per deciliter can be associated with health problems in children.

High levels of lead in tap water can cause health effects. The lead in the water enters the blood and causes high blood lead level. It can cause damage to the brain and kidneys. It can interfere with the production of red blood cells that carry oxygen to all parts of the body.

The bacterial decomposition of organic matter is inhibited by 0.1 to 0.5 mg/L of lead. The toxic concentrations of lead for aerobic bacteria are reported to be 1.0 mg/L.

The effects of small concentrations of heavy metals, particularly lead upon fish, have been studied. Such studies indicate that in water containing lead salts, a film of coagulated mucus forms first over the gills then over the whole body of the fish. Probably as a result of a reaction between lead and an organic constituents of mucus. The death of the fish is caused by suffocation due to this obstructive layer.

Additionally, the toxicity of lead toward rainbow trout increases with a reduction of the dissolved oxygen concentration of the water.

The following table shows factors by which the threshold concentration of lead must be multiplied to determine the concentrations of equal toxicity at lower dissolved oxygen tensions.

Dissolved Oxygen % Saturation Reduction Factor
100% 1.0
80% 0.95
60% 0.85
40% 0.71

Each of the heavy metals is discussed briefly.
Nickel in Water
Zinc in Water

Next Topics…
Non-Metals in Water

Chemical Water Quality Parameters
Pesticides in Water
Oil in Water

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Physical Water Quality
Chemical Water Quality
Biological Water Quality
Water Basics 101

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