Galvanized steel pipe used as a water main, utility 2. (Click here for full-scale image. Free use with attribution)

Galvanized steel pipe used as a water main, closer view. (Click here for full-scale image. Free use with attribution)

Enlargement of previous image. (Click here for full-scale image. Free use with attribution)

Scale composition (mg/kg solid): Cu = 145; Mn = 1080; Pb = 56; Sr = 30; Zn = 1650. Heavy metals are low, except Zn.