The potable water tanks are installed in the FWD area of the AFT cargo
compartment, above the body landing gear boxes (three on the LH side
and three on the RH side). As option, two additional tanks can be installed
(one on each side). Each tank has a capacity of 283 liters (75 US gallons)
for a basic total volume of 1700 liters (449 US gallons).
The potable water is distributed to the galley and lavatory faucets and to
the toilets and Galley Waste Disposal Units (GWDUs) for flushing.
Two compressors fulfill the tanks pressurization. For maintenance, it is
possible to pressurize the tanks by using a ground pressure connection.
Before distribution, a treatment module filters, heats and purifies the
potable water.
The filling of the water tanks is done from the potable water service panel
installed in the AFT lower fuselage. The draining of the complete system
is done from the potable water service panel and from the FWD drain
panel installed in the FWD lower fuselage.
A depress valve, installed near the service panel, is used for system
depressurization on ground.