5 years test result of SS vs other pipes

Stainless steel and other pipes used in city water supply were subjected to five year underground installation tests in 25 cities of Japan. These 5 year test results in Japan have proved that

stainless steel piping (SS 304 or 316) have not undergone any corrosion
the carbon steel (avg - 0.019 mm/yr) and lead pipes (0.002mm/yr) have very high corrosion rates with a maximum corrosion rate of 5-6 times these average rates.
The cast Copper pipes and fittings have undergone frequent corrosion.

Generally speaking, SS 304 pipes didn't develop any degradation at site except slight discoloration and exhibited excellent corrosion resistance. SS 316 pipes were free from even the discoloration.