Sources of Lead in Drinking Water

Lead pipes are the major source of lead in drinking water. In the past, lead pipes were eonsidered to be a eonvenient and suitable material for the conveyance of water. Lead is easily formed, eut and jointed, and its flexibility provides resistance to subsidence and frost. The thickness of lead pipe and its resistance to pitting corrosion also made it a desirable and durable material. 

In most countries lead pipes are forbidden nowad s and lead pipes are only found in old houses. Lead pipes are encountered almost exclusively in the service pipe and internal plumbing systems. 

Whilst lead pipes are the main somce of high lead concentrations, lead concentrations higher than 10 4g/l can also be observed for properties without any lead pipes. Lead-based solders (for copper plumbing), copper alloys (brasses and bronzes) used mainly for fittings, galvanized steel pipes and uPVC (when stabilized with lead salts) can release lead into drinking water. 

Lead based solders (tin/lead solders) contain up to 60 % of lead, which can be released into water through galvanic corrosion. The corrosion rate is increased by high concentrations of chloride and nitrate but is inhibited by sulfate, silicate and orthophosphate. Lead concentrations at the tap depend not only on the corrosion rate but also on the number of leaded joints in the plumbing, the area of solder exposed to water at each joint, and the water usage pattern (Gregory, 1990). 

Experiments on the leaching of lead from copper alloy (brasses and bronzes) fittings suggest that lead is prone to be concentrated on the internal surface during machining, leading to the possibility of elevated lead concentrations from new 

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The main source of lead in drinking water is from lead service pipes and the lead pipes inside dwellings and in the older districts of some Cities and Towns, up to 90% houses may have a lead pipe. Problems can also be caused by lead leaching from devices, pipes and plumbing components made of brass, and from lead-containing solder. 

The main source of lead in drinking water is from lead service pipes and the lead pipes inside dwellings. 

The percentage of houses with a lead pipe varies from 8% to 65% with a regional average of 28%. Other known sources of lead in drinking water ... 

It was generally considered that lead pipes were the major source of lead in drinking water in the region. Assessment of the extent of lead problems before intervention ... 

Quam, G. N. and Arthur Klein. 1936. Lead Water Pipes as a Source of Lead in Drinking Water. American Journal of Public Health 26 778-780. 

It is assumed that the only sources of lead in drinking water are lead service lines and any internal lead pipes within premises and that lead contamination is due solely to the process of dissolution. The model does not simulate lead releases from brass or galvanic corrosion, nor particulate lead releases however, correction factors can be apphed if necessary. 

EPA regulations also limit lead in drinking water to 0.015 milligrams per liter (mg/L). The 1988 Lead Contamination Control Act requires the Consumer Product Safety Commission (CPSC), EPA, and the states to recall or repair water coolers containing lead. This law also requires new coolers to be lead-free. In addition, drinking water in schools must be tested for lead, and the sources of lead in this water must be removed. 

Fluorescein (703) (Acid Yellow 73 C.I. 45350) is possibly the best known xanthene dye. The sodium salt is soluble in water to which it imparts an intense yellow-green fluorescence, detectable even at a dilution of 0.02 p.p.m. under UV irradiation. This property leads to the use of fluorescein as a location marker for aircraft lost at sea, as a tracer for the detection of a source of contamination in drinking water, and in a number of related situations. The use of fluorescein to detect abrasions of the cornea is also based on its fluorescence. 

The major source of high concentrations of lead in drinking water is the dissolution of lead from lead pipes or lead solders used in the distribution system, known as plumbosolvency (Section 3.3.5). In Britain, it is estimated that roughly 7 million households have lead somewhere between the water main and the tap. Many households may thus be exposed to elevated levels of lead in their drinking water (Section 3.3.5). Attention is currently focused on possible remedial actions. 

The United States Public Health Services drinking water standards specify a 50 mg/1 maximum for lead, EPA [73] has shown that this limit is only infrequently exceeded in larger United States cities. The presence of lead in drinking water may result from the use of lead materials in the water distribution system. Naturally occurring lead in rocks and soils may be an important source of contamination in isolated instances but lead from industrial wastes represent a local and not a widespread problem. The disposition of lead compounds from gasoline is a major source of lead in water systems [73]. 

The potentially harmful effects of exposure to high concentrations of nitrates in drinking water result from reduction to nitrites, which combine with haemoglobin to form methaemoglobin (blue baby disease). Additionally, nitrosamine formation can cause cancer and hypertension. In nature, high levels of nutrients, such as nitrates, lead to eutrophication of water sources, which in, severe cases, lead to the extermination of the other aquatic life due the decreased levels of oxygen and luminosity. 

Duplicate diet studies of people living in areas where exposure to lead from other sources is known to be low have provided some valuable information. The mean dietary lead exposure to women was estimated to be 0.31 mg/week and the mean lead exposure to children as 0.11 mg/week.12 These studies included the contribution from drinking water. In areas with elevated levels of lead in tap water, estimated lead intakes of both adults and children are found to be higher and, in a small percentage of cases, above the PTWI. 

Antimony is not usually found in significant concentrations in drinking-water. Concerns that antimony-tin solders would be widely used in place of lead solders have not materialized, Should monitoring be required, this would normally need to be at the tap unless a specific source of antimony in raw water is identified. 

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