The pumps will get about 10% of the water out when they wear out and break down.I don't think much about this author's evaluation on the reliabilty of NOLA's pumps; the A. B. Wood screw pumps are remarkably simple and have little to 'wear' - we are talking LOW head pressures here, virtually NO seals (perhaps a simple packing gland around the drive shaft) and a REALLY long life - PUMPS from the 1915 appear to STILL be in service ...
In short, this author does not know the specifics of the NOLA 'pumps'.
"In short, this author does not know the specifics of the NOLA 'pumps'"
What do you think about his assessment on power costs to pump the city dry?