Water reservoir The water reservoir, seen while looking toward the metal tower, with the channels in the pavement and the doors of the air-tight compartment leaning against the walls. On the right you see one of the niches for water reservoirs (24/06/1999).

The water reservoir for Center 21 differed in several ways from those of the other works. In fact, it did not sit in the usual niche in the wall in the corridor or living quarter walls, but in a separate room in whose side walls two alcoves have been excavated which housed the water containers:

• The room is not big enough to be a living quarters, but is too big to be a simple storage room. Perhaps it had a second function. Since it is located at the bottom of the stairs leading to the metal tower, it is probable that it served as a shelter for the soldiers on duty.
• The second unusual characteristic are the channels in the pavements for the conduits. These channels, which connect with the channels which run half-way up the walls, are not present in any of the other works which we have visited in the Moncenisio area (defensive lines of Pattacroce, Rivers, Ospizio, and Roncia).
• Finally, the presence of two alcoves for the water reservoirs which seem to be too large for the rather modest center.

In order to avoid possible contamination, the locations of the water reservoirs are isolated from the other parts of the works by means of sealed compartments. The first is between a pair of air-tight doors which separate it from the combat post in the metal tower. The second consists of a series of three air-tight doors which are relatively far apart and isolated it from the main entrance and the living quarters.

One of the alcoves for the water reservoirs (the one in the wall opposite to the corridor). Notice the vertical channels which are connected with the channels in the pavements. You see leaning against the wall the metal door which sealed the corridor from the main entrance (24/06/1999).