A switch from free chlorine to chloramine disinfectant triggered problems with excessive
lead in Washington, D.C., drinking water. High levels of lead originated in the service lines, but
excessive lead was also derived from solder or brass plumbing materials. In many cases,
the highest lead concentrations emerged from the tap after about 1 minute of flushing, a
troublesome outcome, given that routine public notification recommended that consumers flush
for about a minute to minimize lead exposure. Bench-scale testing found that chlorine reacts
with soluble Pb+2 to rapidly precipitate a red-brown-colored lead solid that was insoluble
even at pH 1.9 for 12 weeks; this solid did not form in the presence of chloramine. Further
experiments indicated that chloramines sometimes dramatically worsened lead leaching
from brass relative to free chlorine, whereas new lead pipe was not strongly affected.
Includes 51 references, figures.
| Edition : | Vol. 96 - No. 10 |
| File Size : | 1
file
, 370 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 13 |
| Published : | 10/01/2004 |
