Research has shown that higher levels of copper appear in drinking water conveyed through
relatively new copper piping systems; older piping systems typically deliver lower copper
levels in their drinking water. This research contributes field data from a real drinking
water distribution system, providing a better understanding of this phenomenon, as it
relates to treatment considerations and compliance with the Lead and Copper Rule.
Copper pipes and copper levels were sampled from drinking water taps of 16 buildings
with pipes ranging in age from less than 1 to 48 years. Water samples from each building
were collected before and following a 16-hour stagnation period. A piece of domestic
cold water pipe was cut from each building near the tap where the water samples were
obtained and analyzed to determine the mineralogy of the copper scale present using xray
diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) technologies.
The samples showed remarkable variation in scale appearance and mineralogy,
demonstrating the diversity of pipe scales present within a single distribution system. A
mix of highly soluble and relatively insoluble copper phases were identified in the real
world scale. Both stable scales, such as malachite, and relatively instable solids, such as
cupric hydroxide appear in pipes irrespective of age. In many samples cupric hydroxide
and cuprite appeared on the surface of the scale while malachite was in the bulk. Copper
cyanide was also identified in two pipe scales. XPS and XRD are shown to be
complimentary techniques for characterizing complex scales made up of a mixture of
amorphous and crystalline solids Includes 10 references, table, figures.
| Edition : | Vol. - No. |
| Number of Pages : | 8 |
| Published : | 06/01/2006 |
