Drinking water, lead from leaching

Direct release of lead-containing industrial waste-water into surface water or ground-water may ultimately impact drinking water. Lead may also be present in drinking water because of leaching from old pipes, solder, water coolers, or faucets. Some historians attribute the fall of the Roman Empire to the effects of lead leaching from drinking-water pipes and wine casks. 

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. 

Lead levels ranging between 10 and 30 pg/L can be found in drinking water from households, schools, and office buildings as a result of plumbing corrosion and subsequent leaching of lead. The combination of corrosive water and lead pipes or lead-soldered joints in either the distribution system or individual houses can create localized zones of high lead concentrations that exceed 500 pg/L (EPA 1989f). 

At one time canned foods were a significant source of lead because of poor-quality solder joints in the cans. High-acid goods, such as tomatoes, would leach lead from the cans. Finally, contamination of drinking water with lead occurs primarily from lead solder joints or old fixtures and occasionally lead pipe was used to bring water to a home. As with many metals, lead was used in a number of remedies, some of which are still available and used by some ethnic groups. 

One major use of PVC is for pipes in plumbing systems. Here, even though the inexpensive lead stabilizers would be preferred from an economic standpoint, the possibility that the toxic lead could be leached from the pipes into the drinking water necessitates the use of more expensive tin and antimony compounds as thermal stabilizers. Because about one-half of the annual U.S. production of PVC is formed into piping, the PVC formulation used for pipes represents a huge market for companies that manufacture additives, and the competition is very intense. A recently developed low-cost thermal stabilizer for PVC is a mixture of antimony and calcium salts. This mixture has replaced stabilizers containing tin compounds that have become increasingly costly in recent years. 

The grounding of household electrical systems to the plumbing can increase corrosion rates and the subsequent leaching of lead from the lead solder used for copper pipes. Areas where the pH of the water is less than 8.0 may have higher lead drinking water levels as well. 

Lead concentrations in drinking water result primarily from lead leaching from water delivery system and from previously contaminated drinking water sources. In... 

Sadly, this story is more relevant to today s society than you might think. Lead-based solder was widely used for many years to connect the copper pipes in water systems in homes and commercial buildings. There is evidence that dangerous amounts of lead can be leached from these soldered joints into drinking water. In fact, large... 

Lead pipes pose a danger primarily in houses that were built prior to 1920, when such pipes were commonly used7 No matter how old these pipes are, they may continue to leach lead into your drinking water depending on the specific characteristics of the water (that is, lead from the pipes will be dissolved by the water) until they are replaced. Water that sits in them over a period of hours picks up much higher amounts of lead than water that just runs through them on the way to the faucet. However, if your water is hard, your pipes become coated over the years with minerals that protect the water from dissolving lead. ... 

The water mains used to distribute drinking water have normally been constructed from cast-iron, ductile iron, asbestos cement and, more recently, from plastics (for example, MDPE medium density polyethylene). Leaching of lead from these materials does not normally occur. Very exceptionally, lead water mains have been used to distribute drinking water. The only known occurrences are in Ireland where their replacement has high priority (Devaney, 2009). 

The plumbosolvency of a water supply is determined by the quality of the source water(s) and by water temperature. There are exceptions, such as lead leaching from brass and galvanic corrosion effects (see Chapter 1), but case studies indicate that generally the worst lead in drinking water problems relate to the presence of lead pipes. We can therefore focus on the interaction of water with lead pipes. 

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