I have cleaned/lined over 200,00 feet of cast iron water line. The lining was Portland cement and the reason for cleaning/lining was to improve carrying capacity. Some of the pipe dated back to 1890, the newest was 1918. All was bare gray cast iron. Some had been cleaned once or twice before. Old timers said that the water was unusable after cleaning for weeks due to corrosion products. I decide to clean and line. The work was done 1,000 feet at a time and the line was put into service by segments, after a segment had cured for two days. The only thing we noted was a momentary high pH lasting about a week. Prior cleaning was about 40 years earlier and the measured H&W “C’ factor was 49-52. After lining the “C” factor was in excess of 140. There has been no measurable change in “C” factor for 18 years. I cannot comment on the Insitumain process, having used only the Insituform orocess on gravity sewers.
Steve