Page 285 - Corrosion Engineering Principles and Practice

258 C h a p t e r 8 C o r r o s i o n b y W a t e r 259

Aesthetics and Customer Perception
The metals of most interest from an aesthetic standpoint are copper,
iron, and zinc. The corrosion products of copper piping in drinking
water may cause a metallic taste, blue-green staining particles, and
discoloration of the water. Iron species from the corrosion of unlined
cast-iron piping, unlined steel piping, and galvanized pipe may
discolor drinking water, form precipitates, cause rusty water and red
staining of laundry and fixtures, impart metallic taste to water, and
promote the growth of iron bacteria and sulfate-reducing bacteria.
Rusty or red water is one of the most common customer complaints
received by water utilities.
Zinc can cause bitter or astringent tastes in drinking water at
concentrations of 4 to 5 mg/L. High concentrations may give water a
milky appearance at room temperature and a greasy appearance
when boiling.

Premature Piping Deterioration and Economic Impacts
Internal corrosion can have significant adverse economic impacts on
the water transmission and distribution systems and consumer
plumbing. Typically, consumer plumbing is most seriously affected
by internal corrosion because piping is normally unlined and its
diameter is small. Such piping will have a tendency to leak or develop
tubercles that may reduce both flow and pressure (Fig. 8.1).

FIGURE 8.1 Tubercles in a small diameter water pipe. (Courtesy of Public
Works and Services, City of Ottawa)