Plumbing problems in U-boats

Wired's Tony Long recounts the story of how a misbehaving toilet caused the loss of U-1206 in 1945:

U-1206, sailing out of Kristiansand, Norway as part of the 11th Flotilla, was cruising at a depth of roughly 200 feet when the commander, Kapitänleutnant Karl-Adolf Schlitt, decided to answer the call of nature. The submarine was a late-war Type VIIC, commissioned in March 1944. It carried a new type of toilet designed for use at greater depths.

Like a lot of new technology, the toilet was just a little buggy. Schlitt had trouble operating it. When he called an engineer for help, the man opened the wrong valve, allowing seawater to enter the boat.

When the water reached the batteries located beneath the toilet, the boat began filling with chlorine gas, forcing Schlitt to order U-1206 surfaced. Unfortunately for the Germans, the boat was only 10 miles off the Scottish coast, and it was quickly spotted by the British.

The crew was still blowing clean air into their U-boat when an aircraft appeared and attacked, killing four men on deck and damaging the boat so badly that it was unable to dive. Schlitt, seeing the game was up, gave the order to abandon and scuttle.