Feb 9, 2012, 6:40 PM
Post #6 of 10
The issue of lead in water leaching from lead soldered joints comes primarily from basic (alkaline) hard water that has been standing in the pipe overnight or longer. If you are drinking tap water, whether here in Mexico or in Canada or the United States, it is best to flush the drinking water line first thing in the morning. Since a typical toilet flush draws between 1.6 - 5 gallons, flushing a toilet on that part of a house's plumbing, also flushes out the lead that accumulated overnight.
100 feet of normal 1/2 inch pipe only holds about 2 gallons of water. This means that a single toilet flush in the morning easily removes the accumulated lead from that circuit. If you have very large 3/4 inch pipes, (unusual), then every 22 feet of pipe holds 1 gallon. If there is 50 feet of normal 1/2 in. tubing between your tinaco and your kitchen sink, (a typical run of pipe) then running 1 gal. of water through the faucet flushes out the lead. If your faucet has modest flow, then it typically takes a minute of rinsing dishes, etc to flush the line before drinking.
Since the average American uses over 500 gal of water a day, the issue of lead accumulating in drinking water from lead soldered joints really is quite minimal. Mexicans use about 375 gal of water per day per person, so, even with Mexican levels of water usage, lead from drinking tap water is not a significant risk. http://www.data360.org/...ata_Set_Group_Id=757
There has been some evidence that basic (alkaline) water sitting overnight (or more than 6 hours) in chilled-water drinking fountains may have elevated lead levels from all the soldered joints in the refrigeration plumbing. The solution to this is to run the drinking fountain for a minute after it has sat unused overnight.
Our significant lead exposures actually come from typical fishing (handling and biting lead sinkers/weights), from lead in soil and dust, and lead-based paints in older constructions. For comparison purposes, the typical risks from lead in home drinking water are quite low: The health risks from breathing soot particles from passing buses, radiation exposure from airplane flights, second hand smoke from tobacco smokers, from radon exposure, from living at altitudes over 5,000 feet, and regular exposure to sunshine, each pose greater health risks for most people than lead in drinking water. The PNAs from grilling a hamburger or steak also represent greater health hazards than typical lead levels in drinking water. The toluene that bleeds out of common construction adhesives presents greater health risks than typical lead levels in home drinking water. Breathing the THMs present in chlorinated US drinking water during a typical shower presents greater health risks than typical lead lead levels in home drinking water.
If your house has (very old) lead pipes, then all of the above descriptions of health risks do not apply.
Dr. Steven Fry
Ph.D. in Public Health and Environmental Chemisty
E-visit at http://yucalandia.com
(This post was edited by Rolly on Feb 11, 2012, 12:23 PM)