Originally Posted by
Wunwing
In the case of the 707s water disappeared fairly early when the JT3s were fan modified.
When the fan was put on the JT3C, becoming the JT3D, American and Pan Am did a substantial refit programme for their engines and converted them all to fan, but TWA, Continental and Braniff did not and retained their original engines. There must have been some cost reason why some did and some didn't. The TWA ones lasted as such in their fleet until the early 1970s.
The notable feature of water in use was the heavy smoke on departure. Someone more tech than myself can maybe explain why water injection leads to this. Also was it pure water ? The BAC One-Eleven used a water-methanol mix for the same performance enhancement purpose.