Aircraft potable-water system

1. An aircraft potable-water system comprising:

a storage tank that is full when it contains a set amount of potable water and not full when it contains less than this amount;

a ground-fill line having an upstream end adapted for connection to an external potable-water source and a downstream end communicating with the storage tank;

an overflow line having an upstream end communicating with the storage tank and/or the ground-fill line and a downstream end communicating with a drain;

a valve movable between an overflow-open position whereat potable water is not blocked from draining through the drain and an overflow-closed position whereat potable water is blocked from draining through the drain; and

wherein the valve automatically moves and/or remains in its overflow-open position when storage tank is full and automatically moves and/or remains in its overflow-closed position when the storage tank is not full, this automatic movement being caused without manual or electrical interaction with the valve; and

wherein the drain is a drainmast.

2. An aircraft potable-water system as set forth in claim 1 , further comprising a switch that automatically converts between a full condition when the storage tank is full and a not-full condition when the storage tank is not full; wherein the conversion of the switch to the full condition causes the valve to move to its overflow-open position so that potable water can drain through the drain.

3. An aircraft potable-water system as set forth in claim 2 , wherein the switch senses the level of the potable water contained in the tank and converts to its full condition when the potable water reaches a predetermined level corresponding to the storage tank being full.

4. An aircraft potable-water system as set forth in claim 3 , wherein the switch comprises a sleeve that is sealed when the switch is in its full condition and a vent opening when the switch is in its not-full condition.

5. An aircraft potable-water system as set forth in claim 4 , wherein a float is movable between a lower location and an upper location, and wherein the float is in its upper location when the switch is in its full condition.

6. An aircraft potable-water system as set forth in claim 5 , wherein the float is lifted by potable water within the storage tank to the upper location.

7. An aircraft potable-water system as set forth in claim 1 , wherein an upstream end of the overflow line communicates with the storage tank.

8. An aircraft potable-water system as set forth in claim 1 , wherein the upstream end of the overflow line communicates with the ground-fill line.

9. An aircraft potable-water system as set forth in claim 1 , wherein the valve is a pressure-activated valve that automatically closes upon the tank reaching a predetermined pressure.

10. An aircraft comprising a drainmast and a potable-water system as set forth in claim 1 , wherein the downstream end of the overflow line is connected to the drainmast for ejection of tank-overflow water therethrough.

11. An aircraft as set forth in claim 10 , comprising a water station for dispensing potable water during flight, wherein the potable-water system further comprises a water supply line extending from the storage tank to the water station.

12. A method of filling the storage tank of the aircraft set forth in claim 10 with potable water, said method comprising the steps of: connecting the upstream end of the ground-fill line to an external potable-water source; allowing potable water from the external source to flow through the ground-fill line to the storage tank; and stopping the flow of potable water from the external source when potable water is ejected through the drainmast.

13. A method as set forth in claim 12 , further comprising the step of disconnecting the upstream end of the ground-fill line from the external potable-water source.

14. A method as set forth in claim 12 , characterized by the absence of non-automatic adjustment of an overflow-line-associated valve within the aircraft.

15. A method as set forth in claim 12 , wherein said steps are performed while the aircraft is grounded.

16. An aircraft potable-water system as set forth in claim 1 , comprising:

a storage tank that is full when it contains a set amount of potable water and not full when it contains less than this amount;

a ground-fill line having an upstream end adapted for connection to an external potable-water source and a downstream end communicating with the storage tank;

an overflow line having an upstream end communicating with the storage tank and/or the ground-fill line and a downstream end communicating with a drain;

a valve movable between an overflow-open position whereat potable water is not blocked from draining through the drain and an overflow-closed position whereat potable water is blocked from draining through the drain; and

wherein the valve automatically moves and/or remains in its overflow-open position when storage tank is full and automatically moves and/or remains in its overflow-closed position when the storage tank is not full, this automatic movement being caused without manual or electrical interaction with the valve; and

wherein the valve is set so as to not open at cabin pressure when the aircraft is in flight.

17. An aircraft potable-water system as set forth in claim 16 , wherein the drain is a drainmast.

18. An aircraft potable-water system comprising:

a storage tank that is full when it contains a set amount of potable water and not full when it contains less than this amount;

a ground-fill line having an upstream end adapted for connection to an external potable-water source and a downstream end communicating with the storage tank;

an overflow line having an upstream end communicating with the storage tank and/or the ground-fill line and a downstream end communicating with a drain;

a valve movable between an overflow-open position whereat potable water is not blocked from draining through the drain and an overflow-closed position whereat potable water is blocked from draining through the drain; and

wherein the valve automatically moves and/or remains in its overflow-open position when storage tank is full and automatically moves and/or remains in its overflow-closed position when the storage tank is not full, this automatic movement being caused without manual or electrical interaction with the valve; and

wherein the valve is set to activate at a pressure difference greater than the pressure difference corresponding to the maximum expected altitude of the aircraft and the expected minimum cabin pressure.