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I BELIEVE IT IS: "U-Boats also carry air conditioning plants fitted into the Control Room which are known as Klima equipment and are manufactured by Linde of Cologne. It is said to produce dry air at about 15-18 degrees C. (59-64 degrees F.) but this does not have much effect on the temperature in the U-Boat although it greatly increases the comfort due to the fact that the humidity is reduced by 1-1/2% per hour. In addition it may produce as much as 2-1/2 gallons of fresh water per hour which can be used for washing purposes." THE 4 CANISTERS APPEAR TO BE REMOVABLE TO FACILITATE USE OF THE RETRIEVED FRESH WATER ALWAYS A SCARCE COMMODITY ABOARD A UBOAT. INITIALLY ALL SUPPLY MILCHKOW SUBMARINES HAD ONE BUT THIS U-BOAT WAS BUILT LATER IN THE WAR AND MAY HAVE INCORPORATED IT AS WELL....

There were two kinds of fresh water. There was the drinking water (potable) and then there was the condensate water. Let us describe each, one at a time so that a better understanding can be made.
1) The potable water is the most simple to describe.
In the forward engine room there were located two Kleinschmidt Vapor Compression Stills. These stills used an intake of seawater that was all about us. This water was heated to the boiling point. The vapors given off were then passed on to a set of cooling coils to condense and separate the vapors back into liquid water and brine. The two liquids were extracted. The brine was eventually pumped to sea after dumping into the bilge. The resulting "fresh" water is then distributed to the all areas requiring distilled water for use. The most abundant use is that required for cooking, and eating, coffee, dish washing, and the like. A smaller amount is double distilled and taken off in a highly pure form for use in maintaining the liquid level of the batteries. These stills were operated at night, while on the surface and it was a very hot job. If someone were caught wasting fresh water, he would get a turn at the stills. It is not unusual for the man who operates the stills to lose as much as 15 pounds during a patrol.
2) The condensate water:
The general temperature of the ocean water is a little cooler than the air temperature above the water. As one submerges and descends to lower depths the temperature decreases even further. This decline in the water temperature is not necessarily related to the depth. In fact it may follow an unusually radical nonlinear relationship as compared to the depth of the water. Since this relatively cool water surrounds the exterior of the submarine, this temperature is conducted to the interior, resulting in cold interior surface. As all of the days efforts are performed such as cooking, physical activities, and the ever present seeping of water around gaskets and seals; water vapor permeates the atmosphere.The increasing humidity is counterbalanced by being deposited on the cool interior surfaces of the submarine. These dew like deposits condense to form droplets of water which in turn drop from the overhead or simply run down the bulkheads (sidewalls) to the bilge. This again was not the making for a comfortable environment for the crew.
Several methods to solve this problem were used such as applying a layer of insulation on the interior, but the most successful was accomplished by the use of a air conditioning condenser or dehumidifier to remove the moisture from the air. This piece of equipment was located in the forward engine room and assisted in the circulation of air throughout the entire boat (submarine).
Since a great deal of moisture is now gathered in one area the question arises as to what to do with this quantity of water. If it was dumped back to the bilge it would only serve to provide a surface for more vapor to escape to the air. Not really solving the problem at hand but only recirculating the vapors.
By putting this water into a separate holding tank eliminates the evaporation problem and provides another much needed supply of water. Also, reducing moisture in a closed environment reduces everpresent electrical shortage dangers aboard the volatile close environment of a submerged submarine> This water is used for bucket baths, laundry, and other non-consumption requirements. An older and usually wiser submariner would draw off the best condensate water into a bucket for his laundry or bucket bath only after the boat had been on the surface for awhile. The new man on board would soon learn, not to draw stinky condensate water after the boat had been submerged all day; when the condensate water contained all the sweat of the crew, cooking odors as well as whatever else was circulating in the air during an all day dive.

https://fleetsubmarine.com/fresh_water.html