h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

They must have some very strong pumps, or pumps in stages to bring the water up to even the 6th floor of a building since water naturally seems to resist rising more than 32 feet due (I believe) to normal air pressure. The old miners back in the 1800's found that out when they had mines (over in England) that went out under the sea and they became prone to flooding. No matter what they did no single pump would raise the water higher than 32 feet, so they had to stage the pumping. Pump A would raise the water to the level of pump B, which would raise it to the level of pump C, etc. James Burke talked about it in one of the episodes of his 10 part series "Connections" made back in the late 1970's.